Plot holes...

Regarding the parallel universes, I don't know, but I don't think it really matters since it works out the same in the end. Evan is trying to either change the future or create a parallel universe in which everything is "perfect". He retains all the memories of his past lives, as well as gaining a lifetime of new ones, hence the nosebleeds, his brain is overloading and starts to bleed.

His father tried to kill him because of the conversation he had about going back and changing the past. One of the things the father says is that "just by being here you could be killing your mother". Evan disagrees and says that he will go back and make everything perfect. His father having already tried to do the same thing, and realizing that it can't be done, tries to kill Evan as a child so that he won't mess up everything.

He always had that conversation with his fater, but because of the blackout, he didn't remember it. That is why when he goes back to visit his father, the future remains unchanged.

As far as the picture with the knife, I havn't the slieghtist idea why he drew it. However, it was drawn by the adult Evan, probably because he remembers being told he drew it as a child. This may be a case of there being no reason it was drawn, other than that it had to be.

One thing I can't figure out is what actually happened the first time the father made the "movie". It is heavily implied that Evan and Kayleigh actually do have sex, but there is one major problem with that. Everytime that Evan goes back, he only has as much time to change the future as the original blackout lasted.

When Evan goes back to the basement the first time and tells the father never to do anything to Kayleigh again, he is only there for long enough time to take his clothes off, and awake from the blackout confused as to why he is naked. There isn't nearly enough time for the two of them to have sex and then stand back up, not sweating, before he wakes back up from the blackout.

While this is a touchy subject, I am currious as to what actually happened as the movie is purposely vague, but it is important to understading the development of Kayleigh and her brother.