In the "Optical Illusion" segment, the two men testing the 3-D glasses are caricatures of animators Eddie Fitzgerald and Tom Minton. They were the source for the titular characters in Pinky and the Brain (1995), and the tall, skinny one is voiced by Rob Paulsen, using the same British accent that he eventually used for Pinky.
Dropping a 16 ton weight on someone is a reference to a sketch on Monty Python's Flying Circus in which John Cleese's character teaches self-defense against attacks with fresh fruit. The 16 ton weight is one of the defenses.