Plot hole: In what appears to be at least an hour or so after curfew is put in effect, Challis goes to a liquor store. Even if he didn't know about the curfew, why would the liquor store still be open?
Plot hole: At the very end of the film where Dr. Challis sneaks behind one of the computers and turns on the "commercial" in hopes of destroying Cochran and all of his robot employees, once the commercial starts you see some of the employees panic and go into hysterics and try playing around with the computers to try and stop the commercial, but they seem to not know what they are doing. However, though only 20 minutes earlier, Cochran's employees knew exactly how to start and stop the commercial perfectly when doing the "test" on little Buddy and his family.
Answer: He was trying to perform a human sacrifice. He mentioned to the doctor when he was tied up that three thousand years ago, there was a massive sacrifice where the world flowed with the blood of children and animals. Now the planets were aligned again and it was time for a new one in order for the people of his craft to control their environment.
Zorz