i thought the same thing about the Source Code, but the time traveling mind frick ath the end really pissed me off for some reason.
It made no sense to me
Gyllenhaal falls in love with the girlfriend of the dead man that he's wearing as a skin suit. So of course he wants to save her life, despite it being repeatedly made clear to him that it's literally impossible to change anything in the real world from his sightseeing tour of the past. Gyllenhaal's professional opinion to the contrary is "You're wrong," and then he proves it by finally saving everyone on the train by trying really, really hard.