Continuity mistake: When J.D. walks up to the table where his interns are sitting, Keith and Rex are fighting with their table knives and have them crossed. The shot switches to a view from the other end of the table and suddenly Rex's knife is on the table and he is facing J.D. but Keith's knife is up in the air as if he was still fighting with Rex. There is not enough time for Rex to put his knife down and turn to face J.D.
Continuity mistake: Near the end after JD tells the interns he wants them all to wave, they all start waving their arms. The shot cuts to a different view and Rex's hands are instantly back on the table.
Answer: Dan was drinking beer and Cox feared that Dan might get so intoxicated he would fall asleep and drown in the tub.
Mortug