On the picture with his dog Kevin is about 10 years old and now about 30. A dog can't be 20 years old.
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.
When Kevin and Sam are driving alongside the bus, Kevin is yelling for the bus driver to pull over but Kevin's lips clearly show him saying something else.
The film is set in America, but the taxi in one shot got a typical Polish taxi-symbol on the top.