The question of Data's rank is a bigger goof than that. For some reason, the writers seem to have meant for Data to be a Lieutenant JG (even though we know he was already Lt. Commander by the Farpoint mission). At one point in the past, Picard leaves the bridge to Lt. Yar while Data is sitting right there at Ops. And yet, when Picard meets Data for the first time (again), he DOES call him "Commander Data." So, which is it?