Pilot Episode :

When the boys are at Ross’ apartment and Ross contemplates the possibility that there might only be one perfect woman for every man, Joey emerges from what we guess to be the kitchen and delivers the “grab a spoon” speech. When he first emerges from the kitchen, he has no watch on. Halfway through listing the various flavours of ice cream, the camera angle changes and he’s wearing a watch. Later, when we return to the scene in Ross’ apartment and Ross asks “Do the words ‘Billy, Don’t Be A Hero’ mean nothing to you?”, Joey once again has no watch on.