Other mistake: When Joey and Chandler and in the cab on the bridge, Joey quickly stops the cab so Chandler can get out. However, on the screen behind, the background doesn't 'slow down' as Joey does, it just continues as if the cab is going at the same speed. Then, in the next shot, it is still. When Joey sets off again, the background stays the same and doesn't show that the cab is getting faster.
Other mistake: When Chandler says "We just got married. Right there!" and points. We hear a small 'ding' and Monica asks "Is that your ring?" But when Chandler pointed, you can see that all of his fingers except his index finger are closed to his hand. So the ring couldn't have come off.