Revealing mistake: When Jarvis and Tommy are driving to school, and he asked if they got the black guy, the sun is overhead - but when they get to school, and they're walking and talking about it, the sun is to the left - like it's mid-morning around 930. You can see the shifts in the sun for about a span of about 4 minutes during that time. (00:04:50)
Porky's (1982)
1 revealing mistake - chronological order
Continuity mistake: When Brian Schwartz drives away in his sports car, you can hear him shift 4 times. When they show a shot of his car go by, he is only going about 5 miles per hour. (00:48:40)
Wendy: Has anybody seen Mike Hunt?
Meat: Practically everybody in town from what I hear.
Question: How did Tim's dad know about the incident with the black guy and about the fight with Schwartz?
Answer: He likely heard about it around town. Anti-semitism was fairly common at the time so word of someone being beaten in a fight by a Jew would travel fast.
So then, how did he also know about the incident with the black man? It happened clear out of town and the only ones who knew about it were Tommy and Billy since they set the whole thing up and the others didn't know about it until after they run out of the hut.
The rest had been back for a while before his dad showed up. Back then this was a small town and again word gets around real fast.