Friends fans ought to work for the FBI, as the armchair detectives manage to spot the tiniest of details, inconsistencies and bloopers - which is like a needle in a haystack, as there is a whopping 236 episodes of the 90s sitcom.
They also seem to have a nose for sniffing out plot holes; like the bizarre crossover between Julia Roberts' cameo in the show and her latest film which just landed on Netflix, Leave the World Behind.
Here's a head start on the other prominent plot hole involving a guest star:
If you haven't heard, Roberts' character's daughter in the star-studded flick is pretty obsessed with Friends.
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Even while the world is falling to pieces around them, she just can't get her mind off the fact she is unable to watch the finale of the iconic series because there is no internet connection.
But even though the kid is apparently Friends' number one fan who has binge watched every other season, she doesn't seem to cotton onto the fact that her on-screen mother, Roberts, guest starred in it.
The Pretty Woman actress joined the gang for the 1996 episode 'The One After The Super Bowl Part 2', where she plays the role of Susie Moss, the love interest and childhood friend of Chandler, aka the late Matthew Perry.
Obviously, it's a pretty major gap in the plot line - and viewers couldn't believe that it wasn't addressed in Leave the World Behind.
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Fans of the New-York based show have since managed to find another Bruce Willis-sized plot hole in Season 6, when The Sixth Sense star took arguably one of the most memorable guest spots.
The legendary actor portrayed Paul Stevens, the over-protective father of Ross Geller's (David Schwimmer) student girlfriend Elizabeth.
He ended up getting together with Rachel Green (Jennifer Anniston) and they enjoyed a whirlwind romance which gave us many iconic moments - such as Willis giving himself a pep talk in the mirror before belting out The Miracles hit track 'Love Machine', which probably played a part in him earning an Emmy for outstanding guest actor in a comedy series.
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But, as Friends fanatics will recall, Joey, Chandler and Ross regularly discussed their adoration of celebrated film franchise Die Hard, where Willis stars as the Christmas-saving hunk John McClane.
Which begs the question - how did the trio not notice Rachel's new man was their movie hero?
It obviously doesn't add up and some social media users expressed their frustration at the lack of explanation for the huge plot hole, as well as the Friends characters' apparent disregard for a Hollywood legend in their presence during filming.
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One said: "If Chandler and Joey loved Die Hard so much, that would've been brought up at least once in conversation.
"And a build up to a joke nonetheless (or the joke itself)."
Another added: "Chandler, Ross and Joey rent Die Hard and watch it together and then in a later series Rachel goes out with Bruce Willis? How are they not star struck when they meet him?"
A third wrote: "Isn't it ironic how Ross, Joey and Chandler loves Die Hard so much but then when Bruce Willis guested it was no big deal hahaha!"
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And a fourth chimed in: "For guys who loved Die Hard so much, Ross, Chandler and Joey were oblivious to how much Ross's girlfriend's dad looked like Bruce Willis."
Well, they have a point.
Featured Image Credit: NBCTopics: Friends, Bruce Willis, Jennifer Aniston, TV and Film, Celebrity, Die Hard