The bulk of the movie was filmed in The Chiselhurst Caves to enhance the production value, but resetting lights and moving cameras around the natural rock formations proved to be problematic and time consuming.
When everyone has blocked themselves into a control room, Sandy decides to blow the door in with explosives near by. When the door flies off, it blows outwards towards her in the corridor, not inwards.
What are the differences between the US DVD and the German Version?
Despite the fact that the German Version is censored in one scene it also contains an extended dialogue sequence that is missing in the US-DVD. A detailed comparison between both versions with pictures can be found here.