Downtown Crossing (2) - S5-E15
Continuity mistake: When Joey is talking to the Mugger in the hospital room, every time they show her sitting down in her chair or getting up from it the chair looks like it is quite far from the bed, down past the foot of the bed, about 10 feet or so from the guy. But all the other shots she appears to be sitting much closer, only a few feet away from his face. (00:31:35 - 00:38:05)
Downtown Crossing (2) - S5-E15
Continuity mistake: While Joey is talking to the Mugger in the hospital room, her hair frequently changes very suddenly between shots from being tucked behind her ears to hanging in front of them. This goes on during the entire scene; and towards the end as the Mugger dies her hair goes from being in front of her ears, to next shot of her hair being tucked behind her ears but not crying, to next shot of her hair being behind ears, pushed back off the forehead and she is openly crying with tears streaming down from both eyes. The changes are too sudden to be realistic, and at this point her hands are in her lap wrapped in her jacket. (00:34:25 - 00:37:30)
Downtown Crossing (2) - S5-E15
Continuity mistake: The level of ash, and the length of the mugger's cigarette change constantly between shots.
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.