10+ Hidden Details Fans Missed On 'The Big Bang Theory'

This is a good one for those Big Bang Theory trivia nights: What's Sheldon's favorite number and why?

Well, it's 73 and from what TBBT experts tell me, it's because 73 is a prime number!

Now, this doesn't exactly work for every episode.

However, there's an interesting theory going around the ether that Sheldon's shirt color changes based on what he's supposed to feel that episode.

Here are the colors to emotions:

Red is when he's angry.

Orange when he's greedy.

Yellow when he's scared.

Blue when he's hopeful.

Purple when he's supposed to be in love.

Indigo when he finds compassion.

And finally, green when his willpower is strong. Just like lanterns!

It's pretty easy to predict what the main nerds will wear on an episode to episode basis.

Sheldon will often wear a T-shirt over a long sleeve.

Raj likes collared shirts under sweaters.

Leonard (usually) wears a hoodie.

And Howard likes the long-sleeved collard shirts. Dress shirts, if you will.

If you hadn't noticed, Amy's apartment number is actually pretty significant... if you're a math geek

It's actually QA 314, which are the first three numbers of Pi. The rest of the numbers are 3.1459265358979... and so on, and so forth.

Obviously, the guys on The Big Bang Theory are geniuses, but do you know what ages they got their doctorates?

Well, for Leonard it was 21, but for Sheldon, it was 16!

Believe it or not, but there's actually a really cool easter egg on Penny's Fridge. See all those pictures on it?

Well, they're not just of Penny, they're also of the cast and crew!

We are all well aware of Bernadette's voice, heck, how could you miss it?

But, it actually started the show a lot different than it ended up, and the actress who plays her developed it throughout the series.

And yes, this is a piece of trivia that will win you game night.

Her last name is, well, we still don't know.

Howard's room in his mom's house is every nerd's dream.

It's full of toys and other nerdy stuff. But did you know that all the toys displayed are women? Because, you know, he's a perv.

Now this one would be awesome for those Big Bang Theory trivia nights.

Turns out, his second favorite pink liquid is actually Pepto Bismol. It narrowly beat strawberry Quik. Huh.

Apparently, the laundry room gets kind of weird in The Big Bang Theory, and I'm not just talking about Sheldon's really on-time habits.

There's a sign in there that says: "Please keep your clothes on while doing laundry."

So get this, not only are Penny and Leonard opposites to each other, but they're strangely out of place in their own respective friend groups.

Leonard is the only one out of his friends who wears glasses, and Penny is the only one who doesn't!

The last names of two of our favorite characters in The Big Bang Theory are actually tributes to two Nobel Prize winners.

Robert Hofstadter was the winner of the 1961 Nobel Prize in Physics.

Leon Cooper was a Nobel Prize Laureate as well.

So we all remember Kathy Bates as Amy's mom, right?

Of course we do, she gave such an awesome performance it's hard to get her out of our collective heads!

But, did you know she wasn't the only actress to play Amy's mom in the series?

The first appearance of Amy's mom was all the way back in Season 4, where she was played by Annie O’Donnell.

Believe it or not, but the props in The Big Bang Theory weren't always based on nerd culture.

In the first couple of seasons, they were actually a lot more scientific.

Alright, so we all know that Sheldon's mom in The Big Bang Theory is played by a woman named Laurie Metcalf.

She, like the other actors on the show, does a wonderful job.

Well, if we switch gears and go over to the TBBT spinoff Young Sheldon for a moment, we'll see that Sheldon's mother is played by a woman who looks a whole lot like Laurie Metcalf, Zoe Perry.

Well, as it turns out, it's because they're mother and daughter (Laurie Metcalf being the mother, Zoey Perry being the daughter).

Honestly, it's probably the best casting choice they could've done.

This one was probably discovered by some very dedicated binge-watchers. So, whenever you see some characters in the laundry room, most of the time they'll be washing the clothes they wore in previous episodes.

Now that's commitment!

This easter egg came from someone with keen eyes, maybe they even wore real glasses!

That's right, not only are Leonard's glasses not real but after a while, the showrunners found they reflected too much light.

So, they got rid of the lenses.

Alright, so let's go back to that episode with Stan Lee in it.

While it was awesome to have such a nerd icon in the series, there was one man that was missing: Jack Kirby.

Jack Kirby is credited with helping to create so many iconic Marvel characters, like the Hulk, the Fantastic Four, etc.

Unfortunately, Jack Kirby had died more than a decade before the show's run, so they couldn't have him on.

They named the judge that sent Sheldon to jail after him!

While it doesn't compare to having the real thing, it's still a very sweet gesture.

Don't bother looking, you can't find it anymore. However, during the show's run, The Comic Center of Pasadena actually had its own website!

Called thecomiccenter.com, you could actually go there and buy props from the show!

Yes, for his wedding, Sheldon was forced to ditch his nerdy attire and wear a tux. However, he wasn't going to go to a wedding without referencing some pop culture.

He had Flash cufflinks and socks.

Well, if you were really looking to win that Big Bang Theory trivia night, then this would be the answer you'd probably take the trophy on.

Here it is: there are 109 images.

Being big fans of referencing pop culture, they would be remiss to not reference one of pop culture's biggest icons: Star Wars.

There are a lot in the series, but the biggest hidden one comes from "The Pants Alternative".

Sheldon goes and defeats his fear of public speaking by drinking profusely. The next morning, he awakes to a video on YouTube of his antics.

That's where we see that his username is ob1... and if you don't get that reference, why are you even here?

Before he was a nemesis to Sheldon, Wil Wheaton was Wesley Crusher in Star Trek: The Next Generation.

So, when it came time to give him a house number, a lot was considered...

They could have gone with any number in the world... but of course, they needed to do a Star Trek reference.

His house in Star Trek: A NCC-1701 starship.

His house in TBBT: Number 1701!