Deliberate mistake: While Cohagen is on Mars, he calls Richter and chides him for trying to kill Quade. Richter is in a car on Earth, yet they're having a real-time conversation, which is impossible because of the distance. [While this is true, a movie with 4 to 21 minute pauses between lines would take rather a long time].
Suggested correction: This movie takes place an undisclosed amount of time into the future. Absolutely no telling what kind of technological advances could have taken place, in a science fiction movie at that.