"Totally Killer" is a mash-up of "Halloween" and "Back to the Future"
It's a fish-out-of-water comedy with time-travel sci-fi element
The horror element is the weakest part, but the movie is still enjoyable
Kiernan Shipka gives an engaging performance as the lead character, Jamie
Jamie accidentally travels back to 1987 and tries to stop the murders that happened 35 years ago
She teams up with the teenage version of her mother, Pam (Olivia Holt)
Jamie has to convince the would-be victims to listen to her, but they don't
The movie makes a couple of inspired choices in the storytelling, such as flashing back to the future and taking a pointed look at the insularity of small-town life
The slasher scenes are the least interesting part of the movie
The identity and motive of the murderer are never as compelling as the resourceful final girl, Jamie