This slip-up takes place a little past the midway point in the episode, right when the feud between Dr. Kelso and Chris Turk over a lunch spot starts.

To demonstrate his commitment, Dr. Kelso Pages Turk to an empty room, to steal his spot. As Turk Rushes into the room, yelling "I was paged!"

A hand and wrist can be seen in the bottom left, catching the door as he flings it open.

There's no reason to pause, as the hand is there for at least a second, and is even wearing a watch.

So... what is a hand doing down on the floor?