Question: What did Al remove from The Lundys' car to cause it to crash?
Question: At the party, one of the "dumb" guests says that he teaches at a school in Los Angeles. Why is he apparently "dumb"?
Answer: At the time, American public schools, especially those in large cities, were under fire for underperforming, especially compared to those in Japan. It was just a dig on the public's perceived views on education and teachers at the time.
Answer: It was one of the hoses connected to the engine, nothing specific, but to indicate that Al tampered with the vehicle.