Something that I and a lot of us have overlooked for a long time is the fact that Tempus was a technophobe. He couldn't even operate the fundamental controls of the time sled. He needed Herb to drive for him.
Later in Meet John Doe he steals the brain washing device and uses it. One explanation I can come up with is the possibility that they are Tempus variants from different universes all with the same motovation.
In view of all this how was he capable of constructing a time window device?
