Top 10 Big Bang Theory Plot Holes You Didn't Notice

If we take ourselves back to the end of season two, the guys were headed out on an expedition to the Arctic. It’s a once-in-a-lifetime opportunity and one you’d be unlikely to forget, right? Well, if we fast forward to season five in 2011, Leonard shows a woman a sketch of him from Comic-Con dressed as Lion-O from The Thundercats. He claims he’s had it since, yep - you got it - the summer of 2009. Now we doubt that Leonard mastered time travel, but if you do the math, it’s hard to fathom how he could have possibly have been in two places at once.

Penny’s ever-changing family is a bit of a mystery. For instance, she doesn’t seem to know her own father’s name, first naming him as Bob despite his later introducing himself as Wyatt. We also learn she has a sister named Lisa that we never meet. Here’s what we do know about Lisa: her water broke at her own wedding, she shot her husband when they were both drunk and she gave Penny a bikini wax using crayons when they were younger. However, not only does Lisw not attend her own sister’s wedding but no one in the family even mentions her - which begs the question, where and what happened to Lisa?

It’s a happy Valentine’s Day in the Rostenkowski-Wolowitz home when Bernadette announces she’s pregnant - but only to the injured rabbit she and Howard found in the hot tub. Now fast forward to December when their bundle of joy enters the world. Hang on, that can’t be right. If Bernadette knew she was knocked up in February, then we have to assume she’s at least a month into her pregnancy. This would mean they conceived Halley in January and come December, it would mean she’d been pregnant for 11 months. Now, we’re no experts, but we’re pretty certain that’s too long to be pregnant. It must have been super uncomfortable as well - poor Bernie!

When we first meet Penny, she’s an actress/waitress struggling to make ends meet. Luckily it’s Bernadette to the rescue when she gets Penny an interview at her firm to be a pharmaceutical sales rep in season 8. The only problem is Penny has no qualifications or medical background, so it seems highly unlikely that the company would be willing to take a risk and hire her. Don’t get us wrong; we’re glad that Penny’s luck changed - but was their boss so scared of Bernadette that he was willing to overlook all of this?

Raj’s selective mutism was a running gag for many seasons and alcohol was the only temporary cure. However, in an early episode during which Howard is entertaining a lady, the others discuss how to proceed with game night without him. Leonard jokes about splitting Raj in half, Raj fires a comeback, and it seems he’s forgotten that Penny’s there. There’s no alcohol around and no one says a word about it, so either he’s suddenly and temporarily gotten really comfortable around her - or the writers momentarily forgot about his condition. We’ll let you be the judge.

It was an exciting time for Howard when he was selected to go into space. We don’t want to be a Sheldon about this, but in reality it would never have happened. For starters, he has too many health issues. But even if we put a pin in all that for now, there’s also the fact that he barely made it through NASA’s intense training, even getting his mother and fiancee to come take care of him. Despite all this though, real life NASA astronaut and Big Bang Theory guest star Mike Massimino, praised the set’s attention to accuracy during their characters’ time in space, so at least there’s that.

We know that Sheldon is a stickler for the rules and loves a good contract, so you’d think he’d do a better job at ensuring the roommate agreement is heeded to. Both he and Leonard have actually broken the agreement, but these times have seemingly gone unnoticed. For instance, Leonard has had lady friends stay over without giving the 12 hours notice, which Sheldon never even mentions. And despite the contract saying no pets, with very limited exceptions, Sheldon himself adopts a clowder of cats. For someone who claims to have an eidetic memory, he sure forgets things when it’s convenient.

Staying with those cats for just a moment, early on in the series we find out that Sheldon is allergic to cats. However, when Sheldon and Amy part ways in season 4, Sheldon decides to get a cat as his new companion. When he worries that his furry new friend will be lonely, he gets even more cats. But there are no symptoms of an allergy to be seen during this time - not a sneeze or even a sniffly nose. This was clearly an oversight by the writers, but since those cats are just so darn cute, we’ll let it slide.

Fans did get to see the elevator repaired by the end of the series, but what we still want to know is when exactly it broke in the first place! Leonard tells Penny about how it broke, dating it back to 2003. But in season one, Leonard says in 2008 that it’s been broken for two years - dating the break to 2006. Moreover, Howard is seen checking out the broken elevator as if he doesn’t know how it broke, even though a flashback shows that he was actually present and very much involved in the incident. Very strange indeed.

As any Big Bang fan can tell you, no one but Sheldon is allowed to sit in Sheldon’s spot - and if you dared to try, that’s not a mistake you’d be likely to repeat. On some occasions though, we do see some of the others sitting in the sacred spot and conveniently, Sheldon doesn’t say a word. Now we know Sheldon isn’t the kind to let things slide. It also seems unlikely that Sheldon will quietly sit elsewhere if someone else just happens to be in his spot. After all, he did call “eternal dibs,” so this sounds like it may be a case of the writers’ forgetful memories!