When Kevin is talking on his cell for the first time, the background and reflections on the car are from the seminary location, until the film cuts to the tunnel (which magically comes out of nowhere).
When the bus blows up, it's a white bus with red and white stripes. When the bus is burning a few cuts later, the paint and make of the bus have changed entirely, to reveal that the bus actually being blown up was orange and white.
The goof items below may give away important plot points.
When the killer on the videotape in Kevin's refrigerator stops talking (ending with "no cops"), there is a nine second delay before the bomb goes off (one second of this is in slow motion). Later, at the police station, they are playing back the recording that was taken over the phone at Kevins apartment. When the killer finishes speaking this time, there is only a three second delay before the explosion.