Continuity mistake: When young Magneto is struggling with the guards at the concentration camp, the father's star switches from one side of his chest to the other. (00:01:46)
Revealing mistake: Just before Sabretooth grabs Storm at the train station he swats a guy aside who was standing in line behind Storm. You can clearly see a wire attached to the guy to yank him off-frame. (00:52:19)
Revealing mistake: In Toad's final scene of the movie, when he is beginning to fight Storm, he leaps into the air onto the balcony railing. If you look at the back of his belt, his wire is very, very obviously visible. There are several times within the movie when Toad or Storm has a wire showing, but none so obvious as that one.
Continuity mistake: When Rogue sits at the bar, as the bartender cleans a cup, a metal ashtray appears beside Rogues glass of water between shots. (00:11:20)
Chosen answer: You are working under the assumption that Mystique would not believe this either. However, with Magneto in prison and no sign of the senator she could happily take on his identity. Also, even if Kelly was alive, after she gave a press statement backing mutants, it would be unlikely that a politician would change his mind so suddenly again and he would therefore not come clean that it was not him.
Scrappy