Crowning Moment of Funny: In order to return to his apartment without his invisibility being noticed, Nick knocks out a drunk guy, then props up his unconscious body to call for a cab. Hilarity Ensues when he must proceed to moving the guy's lips in order to put up the façade of a talking man. Then, when he reaches where he needs to be, he pretends he has to "vomit" so he can get out.
At one point, the drunk guy wakes up prematurely and asks where they are. Nick has to knock him out again.
Fridge Horror: The invisibility is spreading: the food Nick eats turns invisible, and we see parts of the Magnascopics building where Nick was sleeping that are visible briefly, then it spreads to the parts of the building that remain visible. We never see the area where the building is after that scene, but it can be assumed (since there is no evidence to the contrary) that the invisibility will continue to spread, not just on the surface but into the earth's crust. And the one person that was in the best position to put a stop to it was murdered by Jenkins.
Narm: Nick furiously demanding "I want my molecules back!" of the scientist who was head of the project that inadvertently rendered Nick invisible. In context, it's supposed to be dramatic, showing a bit of Sanity Slippage as Nick is running out of options to become a normal person again. Between the absurdity of the sentence itself as well as the fact that Chevy Chase didn't succeed at Tom Hanks Syndrome, it comes off as ridiculous.