When Leonard is talking to his mother he says "I guess maybe subconsciously I did" to which his mother replied "you mean unconsciously" Leonard was correct and his mother was wrong.. maybe the gag was meant to be the other way around.
In the opening scene, Professor Proton (played by Wil Wheaton) lists the items needed to make his homemade hovercraft: a CD, a bottle cap, a balloon, and some superglue. But since the bottle cap needs a pinhole in it to work correctly, he should have mentioned a pin, or other pinhole-making device.