Teenage boy goes emo again. "I hate you! I wish I were never born!" Okay, he didn't say that, but close.
These high-tech physicians from the future use giant leeches. Leeches? Is that supposed to be funny? Or believable?
Awkward expository sequence explains why colonizing the past doesn't change the future. Makes a forced and non-clever "Sound of Thunder" reference.
It's losing steam. The first fifteen minutes are the best so far. Bring back the cute little girl and the dinosaurs.