When Roger on his motorcycle cuts off Stan there's no train tracks, then they appear when the train goes by.
When Roger goes to the attic to find information about Jeff, his computer and desk are to the left of the stairs behind the railing. When Stan comes to the attic two scenes later, we see Roger's desk has moved. It is now in front of the stairs. His computer and chair have both changed as well.
The first train is traveling right to left at high speed, followed by another train, on the same track, traveling left to right at high speed less than 1 minute later. This would never happen, as there's too great a chance for a collision.
At the end when the cop was arresting Stan, he ended up letting him go without any explanation.