Arrow season 7, episode 13, "Star City Slayer" may have contained the greatest number of surprising twists of any single episode in the history of the Arrowverse. The main plot of the episode saw the return of an old villain in a new identity. This helped clear the path for two of the show's regular cast members to leave the series and set the stage for two more major reveals in the final minute.

Oliver Queen took some time off from work this week to focus on rebuilding his faltering relationship with his son, William. Things were worse than he imagined, however, as William contacted his maternal grandparents to complain about life under Oliver's roof and sent them running to his defense, announcing their intention to sue Oliver for custody. At the same time, the rest of Team Arrow (all now duly deputized agents of the Star City Police Department) began investigating a series of murders that seemed to point to a serial killer. Our heroes also discovered evidence that the so-called Star City Slayer was responsible for the threatening notes which they had all been receiving over the past few weeks.

Related: Arrow: Who Is The Vigilante Stalker In Season 7

Meanwhile, in the future storyline set in Star City 2038, William Clayton continued to search for answers regarding the murder of Felicity Smoak and the bombing plot that threatened Star City. The trail brought him and his allies into a confrontation with the pit-fighter Blackstar and Connor Hawke, in the ruins of the former Team Arrow bunker. It also led to a startling revelation regarding Blackstar's identity and her own reasons for seeking out Felicity Smoak. Yet for all of the revelations this episode of Arrow provided, there are still many questions fans are asking in the wake of the conclusion of "Star City Slayer."

10. Who Is Blockbuster?

Nightwing Blocbuster Cover Cropped

When Dinah Drake calls Captain Singh of the CCPD to get some information on a string of killings similar to those of the Star City Slayer, the two former co-workers start talking about old times and how things have changed since Dinah was an undercover cop in Central City. When Dinah says she still isn't comfortable being a Police Captain and being outed as a metahuman has just made things more awkward, Singh encourages her by reminding her of an old case where she infiltrated the gang of a crime boss in Bludhaven called Blockbuster. Singh says that if it hadn't been for Dinah, hundreds might have died in a gang war that would have shaken the underworld of Central City and that anyone who could accomplish what she did can do anything.

Read More: Arrow Namedropped A Batman Villain Perfect For Batwoman's TV Show

Arrow season 7's mention of Blockbuster and Bludhaven should ring a bell for fans of the Nightwing comic books, where Bludhaven was the name of Nightwing's adopted hometown and Blockbuster was the nickname of a metahuman gangster named Roland Desmond. Possessing superhuman strength and a giant physique, Blockbuster became Dick Grayson's arch-enemy. Given that the Arrowverse Blockbuster was locked up in Central City before the STAR Labs particle accelerator explosion awakened the metagene in hundreds of people, could this be foreshadowing the appearance of a super-strong Blockbuster on The Flash sometime soon?

9. What Just Happened In Central City?

Arrow Captain Singh The Flash

While Captain Singh and Captain Drake are talking, Singh apologies for taking so long to call her back. He explains that some new superpowered criminal just put several CCPD officers in the hospital before The Flash and his allies showed up to stop them and he was busy tending to the aftermath. This doesn't seem to mirror any recent events in Central City, suggesting that this episode occurs concurrently with an upcoming episode of The Flash. So who is this new metahuman menace?

Related: Theory: The Flash's Future Cicada Is Actually [SPOILER]

8.  Why Didn't The Claytons Sue For Custody Sooner?

Arrow The Claytons

When the Claytons arrive on Oliver's doorstep announcing their intention to sue him for custody of their grandson, Mrs. Clayton says they should have taken this step a long time ago.  Honestly, it's surprising they didn't. Even ignoring the events of the past year, which saw William placed in the Witness Protection Program and sent across the country to attend boarding school under an assumed name, his life with Oliver and Felicity was far from ideal. He was kidnapped twice by villains who found out that he was Oliver Queen's son before Oliver ever took custody of him. Things only became worse after season 5, when Oliver moved William into his home after Samantha Clayton was killed on Lian Yu in the Arrow season 6 premiere.

The only reason Oliver took custody of William was because Samantha made him promise to watch over their son with her dying breath. This seemed drastically out of character given how desperate Samantha was to avoid any association with Oliver or the Queen family, even before she learned that he was the Green Arrow. Given that, it's completely unbelievable that Samantha wouldn't have told her parents of her wishes regarding her son's care in case something happened to her or that she wouldn't have told them who the father was and why she wanted him kept out of William's life. Even before Oliver became a convicted felon and a publicly outed vigilante, William's grandparents should have had a solid case that Oliver wouldn't be able to offer a good home as a single-father with a high-profile job as Star City's mayor that took up most of his time.

7. How Does Arrow's Star City Slayer Match Up To The Comics?

Green Arrow Stanley Dover Star City Slayer Mia Dearden from Green Arrow #9

Fans of the classic Green Arrow comics thrilled when they discovered that Oliver's one weaselly ally in Slabside Penitentiary was named Stanley Dover. In the graphic novel Green Arrow: Quiver (which was written by frequent Arrowverse director Kevin Smith), Stanley Dover was a seemingly kindly old man, who took a homeless and amnesiac Oliver Queen into his home after the recently resurrected Green Arrow saved him from being mugged. Stanley was there to play Alfred to Oliver Queen's Batman, as the Emerald Archer rebounded and started investigating a series of child murders perpetrated by a killer dubbed the Star City Slayer.

The climax of Quiver revealed Stanley Dover to be both the Star City Slayer and a practicing warlock. The murders Stanley committed as the Star City Slayer were all part of his plan to draw out a particular demon and gain immortality. Despite both being mentally unbalanced and thinking nothing of killing to get what they want, there is no connection between the comic book Stanley Dover and the Arrowverse version of Stanley Dover, apart from the shared name and their preference for knives.

Related: Arrow: Every Past Character That Returned In The 150th Episode

6. Who Is Virgil?

Green Arrow Virgil The Ninth Circle

When asked how the search for the mystery man called Dante is going, Curtis Holt tells John Diggle that they've made progress. Tracking the phone number Ricardo Diaz dialed to contact Dante while in a virtual reality simulation led them to a figure in Egypt named Virgil, who is apparently one of Dante's lieutenants. In the Green Arrow comics, Virgil is the name of a figure who had dealings with Dante's criminal bank, the Ninth Circle, and just barely got out with his life. It is Virgil who tells the comic book version of John Diggle of the Ninth Circle's existence and the depths of their power.

Page 2 of 2: More Questions From Arrow Season 7, Episode 13

Green Arrow's Famous Chili

5.  Why Is Oliver Queen's Chili Famous?

When a sullen William Clayton returns home from school, still angry at not being allowed to move in with his grandparents, Felicity Smoak tries to cheer him up by telling him that Oliver will be making his "famous chili" for dinner that night. William is less than enthused by this news. In fact, he later says that Oliver's chili is way too spicy and that, despite Oliver's belief that it's his favorite dish, William really doesn't like it that much.

In the comics, Oliver Queen's Famous Chili is a legendary substance likened to the Philosopher's Stone and the Elixir of Life for all the wondrous properties it contains. It can instantly dehydrate an Atlantean and acts like fire within the digestive system of a Martian. The Flash claims to have once used it to negate the effects of Captain Cold's cold gun and both Hal Jordan and Guy Gardner proved unable to maintain the focus needed to make a Green Lantern ring work after one spoonful. Even Superman struggles to finish a bowl, with the only people capable of eating it unscathed apart from Oliver Queen himself being Black Canary and Batman.

4. Isn't It Cold In Star City In The Winter?

Arrow Star City Arial Shot

As William is preparing to move to Central City, Felicity says that she'll have to send him "three coats and mitts and a hat" because "it gets really cold there in the winter." This odd statement adds to the ever-increasing confusion regarding the geography of Central City and Star City and just where they are located in the United States of Earth 1. Previous episodes of Arrow suggested that Star City is located in the same vicinity as Seattle in our world and while Seattle's coastal location is not as cold as some cities in the Pacific Northwest, it still gets enough snow every year that winter wear is required at least a few days out of the year. Then again, William did just move back to Star City and may not have a winter wardrobe. It is also entirely possible Felicity is just playing the role of the over-protective mother.

Related: The Flash: Is Central City Too Big Because of Flashpoint?

3. Is This The Last We'll See Of Curtis Holt?

Echo Kellum in Arrow Season 5

One of the surprise twists of Arrow season 7, episode 13 is that Curtis "Mister Terrific" Holt resigned from his position at ARGUS in favor of a job with the Kohler Humanitarian Institute in Washington DC. Reportedly this came about because actor Echo Kellum wanted to spend more time with his family in Los Angeles than Arrow's shooting schedule in Vancouver allowed. While his appearance in "Star City Slayer" will apparently be his last as a series regular in Arrow season 7, Kellum is open to the possibility of making a guest appearance in future episodes. At this time, however, there are no plans for Mister Terrific to appear on Arrow anytime soon.

2. Do Oliver And Felicity Break Up In The Future?

Arrow Oliver Queen Felicity Smoak Unmasked Stephen Amell Emily Bett Rickards

"Star City Slayer" ended with two shocking revelations. First, that Felicity is pregnant with Oliver's child in the present day. Then, in the flash-forward to 2038, we learn that their child grows up to become Blackstar, whose real name is revealed to be Mia Smoak.

Many fans, particularly those who dislike the romantic relationship between Oliver and Felicity, believe that their daughter taking her mother's last name is a sign that their marriage is doomed to failure. While that is a possibility, it's also a rather broad assumption. For one thing, Felicity is not a traditional sort of woman and didn't change her last name when she and Oliver got married in Arrow season 6. Oliver also isn't much for tradition and isn't the sort of man to insist that his child take his last name.

Another possibility is that Mia Smoak's legal name is Mia Queen, but that she later took her mother's last name because of her holding a grudge against her father for some reason. This could also explain Mia's deep-seated hatred of vigilantes. In any case, there are any number of reasons why Mia doesn't use her father's last name that don't involve an Olicity break-up.

Related: Arrow: Who Killed Felicity? The Clues To Star City 2038's Great Mystery.

1. Where Is Oliver Queen In 2038?

Legends of Tomorrow Star City 2046 Oliver Queen vs. Ravenger

One big question that remains to be addressed by Arrow season 7 is where Oliver Queen is in the year 2038. With two different groups investigating the bombing plot and working to save Star City, it's surprising that Oliver Queen isn't affiliated with either one of them. While some believe that Oliver is destined to die in the upcoming Crisis on Infinite Earths event later this year, Eobard Thawne said that the history books of his time said that Oliver Queen lived until the year 2071. While time can easily be rewritten in the Arrowverse and the timeline of Arrow has already been altered at least once, the question still remains - where is Oliver Queen?

More: Theory: Arrow Is Remaking Legends of Tomorrow's Star City 2046

Arrow continues Mondays at 7pm on The CW.