Visible crew/equipment: Monica is talking to Pete in the diner when he gets back from Japan. If you look at the floor at Monica's end of the counter at the very beginning of the scene, you can see the mat that is there to protect her when she falls over later. (00:02:35)
Continuity mistake: Towards the end of the episode, Ross and Chandler come into Monica's apartment and Ross asks where Rachel is. Watch the objects in Monica's hands, in the shot from behind she puts them on the table, and then does it again in the shot from the front. (00:24:00)
Visible crew/equipment: After Ross breaks up with Elizabeth, when she throws the water balloons at him and he starts walking away, a crew member's feet are seen standing on a windowsill behind Ross. Additionally, when Ross has exited the building, just as Elizabeth calls to him and he turns around we can see a crewmember, presumably standing beside the second camera, at the bottom left corner of the screen. We know it's not a passerby because he is as tall as the second story window behind him, which means he's elevated on a platform or ladder. (00:19:15)
Continuity mistake: After the game at Ross' apartment Chandler takes Phoebe's cursed money, and when Ross wants to settle up with "the big Green poker machine who owes fifteen," Rachel's sitting down at the table in front of Ross, but then it cuts to Rachel who's suddenly standing up near the table. (00:12:30)
Visible crew/equipment: When Phoebe and everyone else hear the guy upstairs with the "pogo stick" Joey gets up to give him the "butt kicking of a lifetime," and just as Joey walks around the couch we can see a crewmember and camera, at the left side of the screen.
Visible crew/equipment: When Chandler points out to Joey that his oblivious comment was made in front of Ross it cuts to a closeup of Ross, and camera equipment can be seen at the right side of the screen, and it's still there in the next two closeups of Ross.
Continuity mistake: After Rachel explains her plan for the fake party, just as Emily opens the apartment door the message written on the Magna Doodle reads "Joey enjoys the," but when Emily and Ross are standing in front of the door the message reads "Joey eats little."
Continuity mistake: At the end, when Monica asks about the garbage bags the apartment's front door is closed, but when Rachel opens the drawer and freaks out about what's inside, the front door is wide open (for the camera) as she kicks the drawer shut, and then the door is closed again. (Widescreen).
Visible crew/equipment: After Emily says thank you to Ross and leaves, when it cuts to Chandler and Joey's apartment Rachel puts a tea bag in her mug, and in the wideshot as she says, "He told me," the camera can be seen at the left side of the screen.
Continuity mistake: When helmet-wearing Vicar Joey taunts Rachel one too many times she turns the tables on him, so when Joey backs away from Rachel he gets pushed up against the front door, and although he can't move, in the shot facing Joey he's at the left side of the door, but in the side shots he's at the right side of the door.