Sheath

I am watching a movie about two boys.

The movie begins with a weird trippy scene explaining that the boy's father did something horrible about 20 years ago and was imprisoned inside a tree as punishment — some sort of weird magical ritual. Years and years later, the boy and his best friend find a plastic sword. When you put the sword into a plastic sheath, it lets you go back in time. They use it to repeatedly get into a car and run over a bunch of people in a gym for some reason I can't remember. After that they keep using it to mess around.

Then they are at a tavern and the sword and sheath are destroyed by their teacher because they are so obsessed with it. The boy runs away from his friend, deeply depressed, and tries to find a way to fix it. Cryptic things keep happening around him — a stranger drops a backpack right in front of him and he takes it as a sign pointing toward a new way to get the sheath back, because why else would that happen?

The very end of the movie has him and his friend getting lost in an infinite tavern or infinite bathroom. It is revealed that this was actually foretold in the monologue at the beginning, where the father told his friend he would end up stuck in an infinite maze.

My description doesn't do it justice — there is way more to it. There is a kid in a bat mask who betrays them, a lot of genuinely emotional moments, and a soundtrack that is weirdly really good. I still have part of it in my head right now.