When Gary takes Phoebe inside the interrogation room, the first shot has the window blinds behind Phoebe closed, the camera switches to Gary and in the next shot the blinds are open behind her as she asks him for some water.
At the beginning, when Monica talks to Gary about Phoebe, right after she says the "funeral" word, first she looks at Gary with a surprised face then when the shot cuts back to Gary and Monica, this time Monica touches Gary's arm without no time to do it so between the two shots.
During one of the ball throwing scenes Ross mentions a mesozoic mastodon. The mesozoic is a geological era from 250-65 million years ago. Mastodons however only appeared from 20 million years to 11.000 years ago, the statement is thus a serious factual error coming from a paleontologist.