it shows us charlies perfect pitch which is a very rare gift to have (the carbon monoxide detector sound)
it shows us how well charlie knows the gang and can predict what they and the health inspector are gonna do (30 seconds to make the noise in the bathroom, knowing dee is gonna sit on the chair so he tries breaking in throughout the episode, understanding their plan without them explaining it to them...)
CHARLIE
half of the episode being one long shot (you can notice the cuts if youre focusing but ssshhhh)
charlie
it shows us how well charlie can measure distances (the dumpster being 5.5 feet away when its supposed to be 6 and dee didnt move it so the health inspector had to log it down damn it dee. maybe charlie can actually count the gas)