Bones has been off the air for nearly a year now, ending in March 2017 after a 12 year run on Fox, the longest ever for a Fox program. The show follows Brennan (a forensic anthropologist), Booth (a FBI special agent), and their team of lab workers as they attempt to solve crime using -- you guessed it -- bones.

After over 200 episodes starting in 2005, the show's fan following slowly declined over the years, largely due to its constantly shifting air time. In fact, the show aired on five different nights of the week and in eight different time slots at some point or another during its run, a tough obstacle for any television show to face.

However, despite the decline, Bones still went out with a bang, boasting over four million viewers for its series finale.

One has to give credit where credit is due -- for a series to have run 12 seasons and have very few major plot holes to show for it is a miracle in and of itself, and the Bones creators managed to create a largely cohesive story over a decade without huge gaps.

The main purpose of this list is to examine the mysteries left behind by the show (particularly its lackluster ending) and explore the questions that would have been answered in future unmade seasons.

With that said, here are the 15 Mysteries And Plot Holes That Bones Left Hanging.

What's the deal with the 447 mystery?

Starting in season 4 and running through to the show's finale, the number 447 constantly appears in the lives of both Brennan and Booth. We see it largely as a time (4:47 on a clock), but also as apartment numbers, security codes, and even as the time of birth for Booth and Brennan's child, Christine.

Fans were excited for the finale, eagerly anticipating the resolution of the mysterious 447. However, other than a throwaway line, the mystery remained unsolved.

The show producers told interviewers that all of the writers had a different idea for what 447 should mean, so instead of providing a concrete answer, they chose simply to make it a metaphor for an important moment or change in the lives of the main characters.

While some may consider this a resolution, most fans felt disappointed that it lacked any big reveal.

How does Angela's unborn child survive a bombing?

Season 12 of Bones offered a happy announcement for Angela and Hodgins -- they were expecting. However, in a crime drama such as this one, being pregnant adds suspense to already suspenseful situations, such as when the Jeffersonian is bombed.

Although both parents survive the explosion, they are immediately worried about the safety of their unborn child, as are viewers. Surely the baby couldn't survive being thrown around and suffering from so much trauma.

Thankfully, Brennan looks for a heartbeat and finds one, and they learn that the baby is still fine. As excited as everyone was, audiences included, it called into question the reality of such a situation.

However, Bones showrunner Michael Peterson says it would have been a shift of tone for the show: "This [scenario] just felt like the one that was most honest to our show ... This is a show where everyone rides off into the sunset."

Are Aubrey and Karen going to get together?

Although the show's finale did not leave any unhappy endings for the characters, it was still disappointing to see how many characters were left with ambiguous endings. Even the most "definite" conclusions to their arcs still left viewers wondering what would happen next. One such instance of this is happened with Karen and Aubrey.

Aubrey was a relatively new character to Bones, introduced in the beginning of season 10 as a young FBI agent who worked under Booth.

In the final episode, Aubrey is joined by Karen, who has brought him some fried chicken and come to console him after a breakup. However, these few moments are as far as this couple's onscreen relationship would go.

When asked about the somewhat inconclusive ending for the two, Michael Peterson commented the lack of finality was to leave room for any show spinoffs that may occur involving Aubrey and Karen.

Will Cam return to the Jeffersonian?

Another character to suffer from an uncertain ending in the Bones finale is Cam, specifically in regards to her future at the Jeffersonian. In the last episode, Cam and Arastoo announce that their six month leave of absence, previously thought to be for a European vacation, is in fact in order to adopt three teenage boys out of foster care.

The couple wants some time off for the children to adjust to the new home and to living together as a family.

Fans were no doubt thrilled with this development, but it also called into question Cam's career. Even Michael Peterson was unsure of Cam's future, which was one reason for the character's ambiguous ending.

He said there was "very much a real chance" that Cam would never return to the Jeffersonian, and that "she and Arastoo will make the tough choices as they look at their careers together."

What made Angela decide to stay in D.C.?

Angela is a pilot character on Bones and has always been portrayed as a restless individual, always talking about her desire to leave D.C. and never return.

She had a love for art and was searching for a chance to go off to Paris and become a famous artist. Given this portrayal, it was surprising for many when, after 12 seasons, she still remained at the Jeffersonian and had no plans of ever leaving.

Michael Peterson offers up a realistic answer to this seeming plot hole -- her priorities have changed. Angela is a wife and mother now and has developed strong relationships over twelve years that would be quite difficult to give up.

Rather than hold on to her old dream of becoming an artist, Peterson says that she's chosen to "make new dreams every single day."

Will the Jeffersonian be rebuilt the same as before?

One shocking twist in Bones' final season occurred in the penultimate episode when the Jeffersonian was bombed. The crime lab had been used by the team in all twelve seasons and was just as familiar to viewers as any of the characters.

Thankfully, the finale shows that no one died in the bombing, and audiences learn that there are plans underway to reconstruct the damaged facility. When the team returns to the Jeffersonian to gather their belongings, they are told repair work will begin the following day.

"They won't change it much, will they?" inquires Angela, to which Cam responds, "They try not to." Audiences never get to see the new version of the Jeffersonian, but given the quote at the end of the show, it's safe to assume it won't be too different from before.

What do Booth and Brennan plan to do now?

Bones - Season 10 - Booth and Brennan

While the series finale of Bones offered a sweet ending -- Booth and Brennan slowly walking off into the night -- many were hoping for a firmer conclusion to the story, with details of how their lives would play out after the show.

Instead, the series ended on an odd note, seeming as if it were another entry in the middle of the series, rather than its conclusion. Michael Peterson offered his thoughts on their lack of finality: "Yes, they’re still going to be out there, and they’re still going to be solving cases and making the world a better place, even if you’re not going to see them anymore."

He continued: "They’re still joking and laughing in the car, having their differences and having those playful fights they have. It’s certainly bittersweet not to be able to see them again, but...they’re all in a good place and they’re going to be okay."

Are the show's methods even real science?

Bones gained its popularity through the unique methods found in the show and brought to light the science of forensic anthropology. As with any show involving real-life science, Bones takes some liberties on what can be done in reality, which creates more than a few plot holes in certain episodes.

Kristina Killgrove meticulously went through each episode of Bones looking for inconsistencies with the show's science and actual science, finding several glaring errors that created plot holes.

For example, the episode "The Don't in the Do" contains a scene in which Brennan uses advanced fusion to determine a skeleton's gender, age-at-death, and height.

This forms the basis for the entire team's case during the episode, but Killgrove writes that in reality, advanced fusion determines "nothing interesting," about a skeleton, let alone key information in solving a crime.

If Dulles International Airport is 25 miles outside the city, why is it shown as a part of Washington D.C.?

Dulles International Airport

Television shows have a long history of misappropriating buildings, streets, and locations for their show, regardless of where the show is said to take place. Bones is no different, using this trick within the opening minutes of the show's opener.

At the beginning of each episode, viewers see a plane approaching what is identified as Dulles International Airport, surrounded by the beauty of Washington D.C. at night.

However, upon further investigation, one can find that Dulles International Airport is 25 miles from Washington, which doesn't even remotely give a view of the city. How is this possible?

The reality of the situation is that Reagan National Airport was the location for filming, but the show creators wanted the airport to be identified as Dulles International.

How does Brennan consistently identify a person's race through their bones?

One of the techniques that Brennan uses quite frequently in Bones is identifying the victim's race by evaluating only the person's skeletal remains. However, in reality, this is much easier said than done.

Elizabeth Miller is the consulting anthropologist to Los Angeles County's medical examiner and coroner, and she spoke out regarding the science of Bones, but more particularly about the show's insistence that race identification is simple and reliable when observing a skeleton.

When speaking about racial identification, she was quick to note the difficulty of the situation. "It's the hardest thing to determine, it is the least accurate, and I'm never surprised when I'm wrong," said Miller, also noting, "Pardon the pun: It's not a black-and-white issue."

Is Zack Addy a serial killer or not?

Zack Addy is an oddity on Bones. Given his back-and-forth character arc, it became apparent that none of the show writers knew what to do with him. The character started as a simple lab assistant to Brennan, helping her in the first three seasons much as the other team members did.

Then, in season three's finale, "The Pain in the Heart", Brennan discovers that Zack had been working with a serial killer the entire time and was plotting against them.

After being jailed, the team later discovers that Zack was imprisoned for a murder he didn't commit, but then learn that he is involved with another killer, the puppeteer.

After much debate and general confusion, they decide that Zack is completely innocent and work to free him from jail. With so much changing in Zack's story, it appears that the writers dug themselves into a hole that they didn't know how to fix.

How does Brennan know so much about other cultures but not American culture?

By all measures, Brennan appears to be a genius in the show. She notices nearly imperceptible details in a skeleton, figures out clues within the human body, and solves even the most difficult cases.

Furthermore, she boasts a thorough knowledge of the customs and qualities of other cultures. In season 2 of the show, Brennan looks into the death of an Asian woman and demonstrates her in-depth knowledge of other cultures and their techniques for anthropological studies.

Despite all of these incredible qualities, Brennan knows next-to-nothing about her own American culture, a bizarre fact to say the least. At different points in the show, she demonstrates just how naive she is, mentioning that she doesn't know who Michael Jackson is, nor the meaning of various common idioms.

If she deems other cultures so important to study, why doesn't she consider it important to learn about her own?

Why did fan favorite Sweets pass away before the end of the show?

Sweets reaches out from Bones

Sweets was introduced in season three of the show and instantly became a fan-favorite. He was a young FBI agent and psychologist, and his comical nature and inexperience added a fresh new twist to the show when he arrived.

His likability and fan support made his death at the start of season 10 completely shocking to viewers. Why on earth would Bones kill one of its most beloved characters?

In reality, the show creators would have loved for Sweets to stay on Bones, as would fans, but actor John Francis Daley needed to move on. Although he loved the show and would have enjoyed staying, he got an offer to direct a movie, which had always been his dream.

He didn't feel he could handle the commitment of acting on the show and directing a movie, so he simply chose to follow his dream.

The same group of people is constantly under attack, so why didn't the government interfere?

Bones' premise leaves the characters open to unfortunate circumstances given the nature of their work. That being said, the team working at the Jeffersonian must be the most unlucky group of people in the country, surviving innumerable attacks and never receiving additional aid from the government.

One would think that after so many incidents, the government would intervene, sending several more FBI agents or even bringing in military assistance to guard the facility and protect the workers.

Over the course of 12 years, characters died (such as Sweets), Hopkins became paralyzed after an attack, and Angela nearly lost her unborn child in a bombing on the facility. How much more would it take before the government would either step in to help or merely decide to shut down such a dangerous and risky department?

Why did the Jeffersonian suddenly get bombed?

Given the dangerous environment in which Brennan, Booth, and the entire team work during Bones, it almost seems surprising that the Jeffersonian did not get bombed until the end of the show.

If they're constantly under attack from criminals, why did it take so long for someone to set off a bomb in their high-tech facility? Doing so would effectively immobilize the team and prevent much of their crime-solving work from taking place.

Unsurprisingly, the bombing had relatively little to do with the plot, and everything to do with the wants of the show runners. Michael Peterson and the other writers have always wanted to destroy the facility, and since the show was ending, the final episodes seemed like the perfect time to do so.

This made the Jeffersonian bombing more of a symbolic act than a necessary plot point. Its destruction signaled that the show had finally come to a close.

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Can you think of any other mysteries and questions that Bones didn't answer? Sound off in the comment section!