Visible crew/equipment: In the scene where Phoebe knocks over the vase, after she says, "Well, that's just the way things go" and turns around to face the babies again, you can see a crew member coming out of Rachel's room. When Phoebe starts looking for the missing baby, the shadow of the crew member is visible on the right of the screen as the baby is placed in the drawer.
Continuity mistake: When Joey walks back into the apartment (with his eyes covered) to get the sandwich, he walks by the Fussball-table, and there's nothing on it. When he walks away you see a purse lying on the cooker. Then, when the shot changes to Dina and Rachel, you see the purse lying on the fussball table.
Factual error: When Monica rolls an 8 to buy everyone a steak dinner, the one die is positioned with a 5 and 4 facing the camera (the 5 on the left, and 4 on the right). With the die that way round a 1 is always on top. There is no other way to get the 5 and 4 combo. This means that Monica had a 7 on the other die, That is impossible. And so she did not roll an 8.