Running for 12 seasons, The Big Bang Theory had countless moments that had fans hooked on the friendship between Sheldon, Leonard, Howard, and Raj. The show continued to grow with the addition of Penny, Amy, and Bernadette, which really rounded out the cast and made for a lot of rewatchable value.

RELATED: 10 Scenes Viewers Love To Watch Over & Over On The Big Bang Theory

After ending in 2019, fans are doing precisely that, revisiting the series and connecting the dots thanks to the spinoff, Young Sheldon. And over on Reddit, The Big Bang Theory fans have shared small details and things they've never noticed during their first couple watches but are just realizing now.

Leonard's Glasses Don't Have Lenses

Leonard gives an interview on NPR in The Big Bang Theory

Leonard's glasses are one of the things fans love most about him. Each character has a specific sense of style that's easily identifiable. Penny loves a good pair of jeans, Howard always wears a dickey and Leonard's known for his thick-framed glasses.

However, one fan pointed out that Leonard's glasses don't actually have lenses in them. This was most likely done to prevent glares from the lights, but it's one of those things that would go unnoticed without Reddit.

Their Sense Of Style

Raj and Howard standing in awe on The Big Bang Theory

With the exception of Penny, the men of The Big Bang Theory tend to wear the same outfits but in different prints and colors. Because of this, it's easy to pick who the best-dressed character is because their style is so consistent.

Howard is typically wearing a dickey, Sheldon wears a graphic tee over a long sleeve shirt, Leonard wear's multiple layers under a light jacket, and Raj loves a good vest. Even Amy and Bernadette stick with the same kinds of clothes (Bernadette is in dresses and sweaters while Amy is in sweaters, skirts, and tights).

Sheldon Did Try Finding The Bird's Owner

Sheldon's lost bird flyer for The Big Bang Theory

In 'The Ornithophobia Diffusion,' Sheldon hated the fact that a bird was calling his windowsill home. He had a fear of birds and wanted them away from his viewing area. After opening his window, the bird flew into his apartment where he had no choice but to befriend it. Bernadette realized that the bird must have been someone's pet, so Sheldon said he'd put flyers up to find its owner.

Related: 10 Facts About The Big Bang Theorie's Leonard Many Fans Don't Know About

Later in the episode, a fan noticed that Sheldon really did make flyers to find the bird's owner and posted them in the lobby. As misunderstood as Sheldon can be, he actually did the right thing in this instance.

Sheldon's Jab At Leonard

Sheldon next to his sick figures on The Big Bang Theory

Viewers love scenes with Sheldon and Leonard because of their hilarious dynamic. Leonard appears to be one of the few people who can live in some kind of harmony with Sheldon. But despite their fondness for each other, Sheldon often throws jabs at Leonard without meaning to.

RELATED: 10 Scenes Viewers Love To Watch Over & Over On The Big Bang Theory

In one scene, a fan noticed that when Sheldon drew stick figures depicting him, Leonard, Howard, and Raj, he made Leonard's stick figure intentionally smaller than the others. This reflected real life, of course, but it's a subtle jab picked up on by Reddit.

Penny Really Cares About The Environment

Penny's enviornmental purse on The Big Bang Theory

At the start of The Big Bang Theory, Penny tried acting like she was environmental in some kind of way by claiming she was a vegetarian, which was a storyline that didn't make much sense.

It didn't take long to prove that Penny didn't last a vegetarian and didn't hold much of the green footprint that she put off. Funny enough, a fan noticed a bag in the background that said "A woman can tell a lot about a guy by the size of his carbon footprint." Now fans are wondering what Leonard's carbon footprint is like.

Is This Directed Towards Leonard?

The laundry sign in the laundry room on The Big Bang Theory

It was hard for fans to let go of seeing Leonard strip down to his undies in the laundry room on two occasions. In one scene, Leonard wore nothing but the roommate flag around him as he did laundry (as a way to bother Sheldon, of course).

And in another, he stripped down to try to sleep with Penny in the laundry room (which Penny denied). Funny enough, after these moments, a sign was spotted in the background that says "Please keep your clothes on while doing laundry." It makes one wonder if the landlord caught Leonard during one of these occasions.

A Connection To Former Shows

Leonard and Penny's wedding party on the Big Bang Theory

Leonard and Penny's relationship timeline was fuzzy for a while, but it became better than ever when they tied the knot. During Leonard and Penny's vow renewal, viewers finally got a chance to meet Penny's mom and brother.

Fans of Kate Segal recognized her immediately as Kaley Cuoco's (Penny) mom in another sitcom, 8 Simple Rules. Fans loved that the writers brought this dynamic duo back together as mother and daughter in different worlds. Similarly, fans realized that the show also did this for Johnny Galecki (Leonard) and Sara Gilbert (Leslie Winkle) who were siblings in Roseanne.

Penny Looks At The Camera!

Penny looks at the camera twice on The Big Bang Theory

As a main character, Penny had some of the most screen time in the series. Whether it was her friendship with Sheldon, her efforts in becoming an actor, or her relationship with Leonard, Penny was constantly involved.

So much so that fans realized there were a few occasions where Kaley Cuoco slipped and looked directly into the camera. As a show that was not a mockumentary of sorts, it's humorous that the show kept Penny's small glances towards the camera in the final product.

Sheldon & The Psychic

Sheldon and Penny go to a psychic on The Big Bang Theory

In 'The Psychic Vortex,' Penny brings Sheldon to a psychic to try and convince him of believing in the things she believes. Sheldon, however, was a hard sell. He didn't believe a thing that the psychic was saying. But after a few rewatches, a few fans pointed out that the psychic actually predicted Sheldon's future.

The psychic noted that Sheldon had someone special in his life and once he let go of his grip and let her into his life fully, he'll achieve success. That's exactly what happened for him once he and Amy got engaged and tied the knot.

An Inconsistency With Barry Kripke

Barry Kripke raising his eyebrows and looking unimpressed in The Big Bang Theory

Is Barry Kriple playing basketball with Sheldon one of the funniest scenes? With both men unfamiliar with sports and unathletic, they hit a wall when they decided to play a game of basketball one day. But one fan pointed out the inconsistency with Barry.

For someone without an athletic bone in his body and who acted as he had never worked out before, that quickly changed when he taught the gang how to fence, talked about rock climbing, and even worked out at the gym with Mrs. Davis. If anything, Barry should have beat Sheldon in this basketball game.

NEXT: Each Main Character's Funniest Scene On The Big Bang Theory