If you spend a lot of your time on the Internet then you'll probably be aware there's loads of stuff in Friends that people missed the first time, only for it to be rediscovered 12 years after the series finale.
There have been theories as to why Jennifer Aniston's nipples are always showing, fans have noticed famous scenes where Matthew Perry almost cracked-up, and people have even spotted pies going missing from tables when Brad Pitt appeared on the show. Oh and there's the moment an extra chewed her coffee.
But there's also this one where Courtney Cox is clearly replaced with a double.
Credit: Warner Bros.
Not Monica! Credit: Warner Bros.
And this avid Friends
fan has noticed...
"I must've seen every Friends episode a million times and never noticed the world's worst stand-in for Monica," the person wrote, alongside a clip of Courtney Cox nodding at Lisa Kudrow's Phoebe - only to suddenly morph into someone completely different when the camera changes angle.
This isn't the first time viewers have spotted an obvious stand-in.
In Season 9, a stand-in for Rachael appears behind Joey in Monica's kitchen...
That is not Rachel!! Credit: Warner Bros.
Why couldn't all the actors just be in all the shots? Was it too much to ask?
Featured image credit: Warner Bros. Television