Corrected entry: In the episode where Phoebe's grandmother keeps lying to Phoebe about her father, Phoebe goes to visit her father and tells Joey and Chandler that, 'What if he's not this great dad. What if he's still the same guy who ran out on my mom and us before we were born.' But in the episode where Phoebe meets her dad at her grandmother's funeral, her father talks about how he burnt the formula, and put on Phoebe and Ursula's diapers backwards. Thus Phoebe and Ursula must have been born before Frank left.
Corrected entry: Whenever exterior shots of Ross' apartment building are shown, it is across the street from Monica's apartment building, which is the side that doesn't have balconies on, however Monica and Chandler are able to see into Ross's apartment from their balcony. Even if their apartment does have a balcony on the back, Ross's building is on the wrong side of theirs.
Correction: Ross' apartment is across the alley, not across the street. Ross lives on the same block and the apartments face each other across an alley.
Corrected entry: There's an impossibility with the view out of the guys' apartment. Take a look at the hallway set: On the left there's the door to their apartment, then a wall, then the stairwell, which runs on the other side of the guys' kitchen/bathroom/living room. Yet when you go inside and see that same wall, it's got windows that show a direct view of outside. Those windows could only show a view of the stairwell.
Correction: The space betwen the stairs and the window is fully valid. Note a few things. These stairs go back and forth, as in they are not one continuous flight. Second, the floors are close together enough that there would be few steps. This allows more then enough room for a window, hence making the view entirely possible.
Corrected entry: At one point Ross goes out with a girl whose father is played by Bruce Willis. In The One With The Nap Partners, Ross and Joey are really excited because they rented 'Die Hard' which stars, Bruce Willis. Monica's credit card is stolen in the 1st series by a woman who hated the film 'Dead Poet's Society', in a later episode Robin Williams turns up in a cameo role. It would be interesting to see who stars in those films in the Friends 'Universe'.
Correction: When Ross is going out with the daughter of "Bruce Willis", he is actually going out with the daughter of a man called Paul Stevenson. Just as in Friends 'Universe' Ross is Ross, not David Schwimmer, Paul Stevenson is Paul Stevenson, not Bruce Willis. Hence Bruce Willis can easily star in Die Hard. And same with Robin Williams and all the other special guests.
Correction: Phoebe could have easily been told that Frank Sr had left before she and Ursula had been born and not realised he had left when she was a young baby. Her grandmother did tell a lot of lies about Frank so she may have been the one to tell Phoebe this as it may seem less hurtful.