At the end when the MPs take Jack Nicholson into custody, he is wearing a tie. Then he lunges toward Tom Crusie and drops his hat. He bends down to pick it up, and the tie is missing.
I saw this the very first time I saw the movie. The tie is still there but during the struggle, which took more than 1 take and was edited, the tie went underneath the collar. If you look closely you see it. But, then the next shot has the tie being front and center again.
It has been a few months since I last saw this movie, so I could be wrong, but I think when Jack Nicholson's character lunges for Tom Cruise, his uniform jacket gets moved in such a way that you can't see his tie. After the MPs let go of him again, Jack straightens his uniform jacket. But watch the movie and judge for yourself.