internally inconsistent time travel

Rating: 4/10 (22 January 2005)

*** contains minor spoilers but nothing you couldn't figure out from the trailers***
The Butterfly Effect was well done as a movie but I always get annoyed when the time travel is internally inconsistent.
There are two ways to imagine time travel, The "Somewhere In Time" (SIT) way and the "Back To the Future" (BTTF) way. In the BTTF way there is a base reality involving no time travel. Someone goes back in time, changes some stuff, comes back to the future and things are different so Marty fixes his life. In the SIT way there is no change. The original time line already has the time travel and any changes the character makes in the past only make the original future possible so Christopher Reeve is doomed. If you only use one of these types your story should make sense.
In "The Butterfly Effect" the black outs don't work. He has a black out because he goes back to that time but in the base reality sometimes he changed something and sometimes he didn't. One example is when he picks up the knife. He wouldn't pick up the knife until he messed up a lot of other points in his life but the movie continues on and those points aren't messed up yet so he had no reason yet to pick up the knife. Almost all of the black outs are sloppy like this but I don't want to reveal the whole movie.
Even though much of the movie is very well done, the lack of a sound foundation makes the whole thing flop. You go away from the movie saying "That wouldn't work."