At the part of the episode where the Main group is on the train, a road block is set up and Lincoln climbs over the main car and into the conductor car. The camera angle shows from the front of the train and the cops in the road block are gone. Then they show from the road block and the cops are on the tracks, then back to the train and they are gone. This continues until the train plows through the road block.
When the train is about to ram the police cars there's several shots were the police officers are standing by their cars waving their hands so the train will slow down, in the next shot the guards clearly disappear from the scene, then return again when the train crashes into the police cars.