Character mistake: The Rufus hologram states that he first brought the phone booth to the Chosen Ones (Bill and Ted) in 1989, referencing events of the original film. While that was the year the first movie came out, it took place in 1988 (indicated by the opening title card and dialogue throughout the movie).
Character mistake: When the camera pans to the frame containing the picture of Lars with his departed mother, the caption says "In memory of our beloved mother Mirra Gunnarsdottir", with a plain O. On the cross, her name is Mirra Gunnarsdóttir. It's two different letters, and it'd be pretty strange to honor the memory of your mother printing a photo with her name in the wrong form. (00:01:10)