When Alan falls over the cat and lands in the bathtub, his legs are sticking straight up in the air. His feet can be seen, even though he can't. When the angle changes, his legs are down and his feet can't be seen.
The ice cubes in Jake's orange drink change from being visible above the surface level in the glass to being completely submerged.
When Alan finds Charlie at the bar he orders a "Sea Breeze" cocktail, with extra pineapple. A Sea Breeze cocktail has a garnish of lime, every now and then a piece of grapefruit. There is no pineapple garnish in a Sea Breeze.
Contrary to what CC displays, pretty sure he orders a Bay Breeze, which is often garnished with pineapple.
In the episode, "Pinocchio's Mouth", Charlie complains that it's 45 minutes, one way, to Chelsea's apartment in Studio City. This would make it unlikely that the pizza guy who delivers to him in Malibu would deliver to Chelsea's place (unless the pizza guy works at more than one location for the same pizza chain).