Visible crew/equipment: When the elevator stalls, Ted and Gooch start singing their state songs to Cox and Kelso. As they start their song for Arkansas, a boom mike momentarily dips just a bit into frame at the top.
Continuity mistake: When Drew and Denise are having their awkward moment in front of the elevator, watch the background. Colonel Doctor walks by twice in the same direction.
Continuity mistake: In this episode Cole has a mole that is found to be cancerous, the mole is not seen in any other episode. He is topless in many episodes and the mole is not in any other one.
Continuity mistake: When Kelso and Cole are sitting in the bed talking, watch the position of Kelso's arms and the juice box he is sipping from. The juice box, straw, and Kelso's arms all move around from shot to shot for the entire scene. Towards the end of the scene there is even one point where Kelso puts his arm down, the shot changes, and Kelso puts his arm down again.
Our Thanks - S9-E13
Continuity mistake: When Dr Cox "wins" the "pinball game" with Denise about what Trang is to do, he leans in to him and says "go go go." The next shot of Trang running off has Dr Cox standing straight upright.
Answer: No, it was a fake, they used a stamp.
It is real.