Continuity mistake: Near the end of the episode when Audrey goes into the dorm bathroom to empty the whiskey bottle, she accidently drops it on the bathroom floor. You can see the bottle smash, with the large label lying flat on the floor and the rest of the bottle (also with a smaller red label) sliding a little to the right. But later when Joey comes in and looks over at the broken bottle on the bathroom floor, it suddenly looks different. Most of the bottle is with the second red label part, and the first part with the larger label lying flat isn't anywhere near it.
Factual error: When Harley talks Joey into calling Eddy's parent's home in Worcester, Joey picks up the old dorm phone that has a handset cord attached. This doesn't make sense, because since Joey is calling long-distance to Worcester she would be more likely to use her cell phone which probably has a pre-paid plan. The old black phones are standard land lines, that come in the dorms; but the roommates both have cells and they also have a more modern wall phone.
Answer: It's only explained once in the series. Jack says to Andie "I tried to start kindergarten without you", meaning Andie was smart enough to start school early.