Andrew Davis was attached to direct the picture based on a different screenplay. The budget being too high and creative differences arising, Carolco hired Roland Emmerich, fresh from his low budget feature Moon 44 (1990) and a canceled Sylvester Stallone vehicle "Isobar", to deliver a new screenplay and direct the film.
In the canyon scene the weather is partly cloudy, however when the mobile command center falls off the cliff, the sky is clear blue. In the next shot, the sky is clear and taken near sunset, not in the afternoon.