There’s a lot that can in 12 seasons of any sitcom. Over time, facts on the show can get jumbled and misshaped, with writers hoping viewers don’t notice the small flubs. But when viewers binge-watch these shows, inconsistencies begin to come to light.

The Big Bang Theory is no different. We’ve fallen in love with the bonds between Sheldon, Leonard, Howard, Raj, Penny, Amy, and Bernadette (you too, Stuart!). However, after 279 episodes of one show, inconsistencies are bound to happen and we have 10 of them!

WHAT’S THE REAL REASON WHY THE ELEVATOR DOESN’T WORK?

The long-running gag on the show is how their elevator doesn’t work. The gang walks up four flights of stairs every single day. When the landlord is going to fix the elevator is a question that pops up quite often.

We finally find out what really happened to the elevator after Leonard told Penny the history of his friendship with Sheldon. What doesn’t make sense is that in the first season, they mentioned the elevator didn’t work for two years, but by the third season, they mentioned it didn’t work for three years. Considering they’re the ones who broke the elevator, shouldn’t they know?

PENNY’S APARTMENT LAYOUT CHANGES FROM THE FIRST EPISODE

In the very first episode of The Big Bang Theory, we see Penny moving in across the hall. Leonard catches her moving packages in her apartment when he instantly falls in love with her.

As you can see from the picture, the layout of her apartment seems different from the apartment we know very well. Typically, when Penny opens her door, viewers are able to see her kitchen right behind her, but in this view, the kitchen is nowhere to be seen.

PENNY ALSO USED TO HAVE A SISTER

When Leonard and Penny finally get married in an actual ceremony, we meet her family (finally!). We meet her dad (which we’ve already met), her mother, and her problem-child brother.

What confused fans of the show is that Penny mentioned in earlier episodes that she had a sister named Lisa. She mentioned that Lisa shot her husband and that she had a nephew thanks to her. Well, if that were true than where was Lisa on the biggest day of Penny’s life?

BERNADETTE AND HER RELATIONSHIP WITH KIDS

As we know, Bernadette and Howard go on to have two precious kiddos. However, before the two got married, Howard learns that Bernadette wasn’t a fan of children. When she accompanied him in a magic show for a child’s birthday, she was very hostile and rude to the kids. It was clear she didn’t have that natural maternal instinct.

However, a fan on Reddit noticed that when Bernadette explains her hesitations to Howard, she says how her mother worked all the time and she had to watch all her siblings (where are her siblings, by the way?). She grew tired of all the screaming and crying and cleaning. However, in earlier episodes, Bernadette claims to be great with kids because her mother ran an “illegal daycare in their basement.” So, what is it, Bernie?

DOES LEONARD SNORE OR NOT?

We love Leonard and all of his little quirks. His asthma, his lack of coordination, and even his apparent snoring. But just how bad was his snoring? Sheldon seems like a pretty light sleeper who’s scared of any potential threat that can occur during one’s sleep and yet he never mentioned a thing about Leonard’s snoring until later in the series.

In the third season, Sheldon mentioned that Leonard didn’t snore but Penny did. And yet a few seasons later, all of a sudden Leonard has this atrocious snoring issue due to a deviated septum. If that were the case, wouldn’t he have a snoring issue back when Sheldon claimed he didn’t?

DID SHELDON CARE ABOUT HIS SPOT AS MUCH AS HE SAID HE DID?

One of the best parts of the show is Sheldon’s addiction to his “spot.” He has a special spot on the couch that only he can sit on and whenever someone else sits in that spot, Sheldon makes it known that he has a problem with it.

However, if you go back and watch earlier episodes, you’ll notice scenes of Howard, Raj, and Leonard sitting in his spot without so much as a glare from Shelly. If he didn’t care in season one, when did his obsession with his spot start?

WHAT’S PENNY’S DAD’S NAME AGAIN?

When Big Bang Theory wrapped up, fans of the show started re-watching their favorite sitcom to fill the void. Young Sheldon is fantastic but nothing beats the original. Now that we’re rewatching the series, Penny mentions in “The Maternal Capacitance” that her father’s name is Bob (who always referred to his only daughter as “little slugger”).

But when Penny’s dad comes to visit (and she pretends that she and Leonard are still dating), his name is suddenly Wyatt. No offense to the writers of Big Bang, but it appears they didn’t know how to handle her character’s background.

SHELDON’S ALLERGIES ARE SOMEHOW IGNORED WHEN HE ADOPTS CATS

In the beginning of the series, Leonard mentions he and Sheldon don’t have any pets because Sheldon is allergic to most cats and dogs. Knowing Sheldon the way we do now, that makes sense.

However, in “The Zazzy Substitution,” Sheldon goes through his first break up with Amy Farrah Fowler. To fill the void, he adopts cats who soon flood his apartment. Knowing Sheldon as well as we do now, why would he adopt all these cats if he was allergic? And how come his allergies never flared up when Raj brought Cinnamon over?

AND HOW CAN HE BE A TAURUS IF HIS BIRTHDAY IS IN FEBRUARY

For the most part, Sheldon keeps his birthday a secret but that changes when finds out. Nevertheless, in “The Peanut Reaction,” it’s revealed that his star sign is a Taurus, making his birthday between April 19 and May 20.

However, in later episodes, it’s hinted that Sheldon’s birthday is around the month of February. If that’s true, Sheldon wouldn’t be a Taurus, he would be an Aquarius.

LET’S TALK ABOUT RENT

One of the biggest questions on the show (for years) is how Penny affords her apartment. As a struggling actress and waitress, it makes no sense that she can afford an apartment of that size on her own in California. If she could afford it, then she would have no money left over for food or activities (like her love for drinking and dancing).

At one point, Sheldon even noted that if he could afford his apartment by himself he would but he needs Leonard for half the rent. If two physicists at Caltech can’t afford their apartment by themselves, how can a waitress at the Cheesecake Factory?