Time Chasers (1994)

Nick creates a time machine out of an airplane and a Commodore-64, and shows it to his friends by taking them 50 years into the future. Nick sells the technology to Gen-Corp, a high-tech firm run by J.K. Robertson, whose office is in the mezzanine of a shopping mall. Robertson, however, turns out to be Evil, and uses the time machine to plunder the future. With the lives of himself and his friends at stake, Nick needs to use his time machine to travel a week back in time and convince himself not to give the demo to Robertson.