Many magicians have specifically stated that people have reported seeing things in their act that they didn't do. James (The Amazing) Randi tells one such story:

Many years back, I appeared on the NBC-TV Today Show doing a "survival" stunt in which I was sealed into a metal coffin in a swimming pool in an admitted and since-regretted attempt to out-do Harry Houdini, who had performed the stunt at the same location back in 1926. Yes, I beat his time, but I was much younger than he had been when he performed it. I had listened to an agent who assured me that this was the way to go. I have been ever since trying to forget my disrespect for Houdini. But this digression is not pertinent to the main story here.

A week following that TV show, I was standing out on Fifth Avenue in a pouring rain, supervising through a window the arrangement of a display of handcuffs and other paraphernalia that I'd loaned to a bank for an eye-catching advertisement. My raincoat collar was up about my ears, and I could thus not be easily recognized. I was astonished when an NBC director, Paul Cunningham, who had been in charge of my swimming-pool appearance, happened by. We were adjacent to the NBC studios, and he had been on his way to work. Not noticing me, but seeing my name on the bank- window display, he began excitedly describing to his companion how I had been handcuffed, wrapped in a strait-jacket, and sealed into the coffin before being submerged, on his show. "And he was free and at the surface within minutes!" he exclaimed.

With a certain small show of drama, I identified myself. Paul was ecstatic, and invited me to join them for coffee. There, while we warmed ourselves over java, I explained to him that he had unwittingly provided his listener with a description that was not only untrue, but impossible. I told him that no handcuffs nor straitjacket had been involved at all in that event, and that he was mixing up his memories of previous shows with the one he had directed. In addition, I pointed out, it is impossible to place a straitjacket on a person who is handcuffed; this is a topological paradox. In addition, I'd not made an escape from the coffin, nor had that been the stunt: I was merely surviving on a limited amount of air, and I was able to climb from the coffin when it was brought to the surface. Cunningham's version was dramatic, but simply very wrong.

Ulric Neisser is probably the person to start with this type of false/malleable memory problems. I have only found interesting things on google book search which do not lend themselves to quoting. Also I couldn't find much more recent studies in this field.

http://www.youtube.com/watch?v=BnFJ8cHAlco

This was repeated at least once.