When Dave is eating ice cream (and watching a movie) at Steve's house, the amount of ice cream on his shirt is changing (he's cleaning his face, but not his shirt)
After the talk with Lupe in her car, in the next shot of night city, the traffic is moving backwards.
When Steve Ford jams door with shovel, you can clearly see someone standing behind the door, though it would mean that someone from Spyder's gang is there and knows about Steve's presence in garage.
When Steve walks in on Dave eating ice cream while watching a movie, Dave's shirt at first is very messy, but suddenly cleans up.
Jason Momoa's character is listed in the credits as "Spider". In the movie they repeat several times that his name is spelled with a "y".
At around 1h15 into the movie there is a scene played backwards. You can clearly see all cars driving on the highway going backwards.