Revealing mistake: Near the beginning of the show, Mark's father puts a bulb into an old slide projector. Then there is a small explosion with smoke and flames - watched carefully, we can see are actually coming from the other side of the projector - the flames can be seen shooting parallel and close to the floor, which wouldn't have happened if the explosion actually came from the projector.
Continuity mistake: When Carter goes into the lounge, he leans his crutches against the lockers and then moves his bag off his shoulder. One crutch falls to the floor, then the bag, then the other crutch. When the shot changes to show these items on the floor, the bag is lying neatly on top of the crutches - an impossibility due to the way they all fell.