Speed Trap - S2-E6
Continuity mistake: When Alex falls asleep after he and Steven are talking in the room about the dangers of the pills, there is an alarm clock on the nightstand next to the bed. Next scene, the parents come in and wake up Alex and suddenly the alarm clock disappears and is nowhere to be seen anywhere around.
Continuity mistake: When Alex tells Jennifer to play her clarinet outside Jennifer complains that its dark out, but you can see through the window that it is bright out. When they show it again it is dark.
Answer: A scene very similar to the one described happened on the show Mr. Belvedere that was on in the same time frame as when Family Ties was on. Perhaps this is what you are remembering.
af4dable ★