FAQ

Cox wanted to make Jack and his family think that after he got his money, he would let them all live. From observing them at the start of the film, he knew they considered Rusty to be a part of their family. If he had killed Rusty, they would've know that he had no intention of letting them all live. Thus, his plan would be ruined.

This is one of the problems Richard Roeper had with the film.

Both Firewall and the original title The Wrong Element refer to the same thing. Cox and his men who stand between Jack and his family.

The Alternate Version that was released on DVD differs from the original Theatrical Version. One short sequence was trimmed in the Alternate Version showing the dog sitting on Janet's lap, whilst the ending was re-arranged as well: different angles and shots were used including an overhead crane. As to why the change was made, actual reasons are unknown, but it is speculated that the abruptness of the movie's ending in the theatrical release left audiences in a state of disbelief towards having no real explanation towards the aftermath of the events of the movie's climax. The change having added two police cars arriving to the scene was meant to create some kind of closure to the film, although it doesn't really add much of anything else that wasn't already there.