Other mistake: After greeting Crusher, Data explains where Picard is. Problem is he uses the contraction "he's" instead of "he is." Data is supposed to be incapable of this.
Suggested correction: This is only a mistake if the series is taken as a whole. At this point in the series, that particular trait wasn't part of the character. Data uses contractions multiple times in the first season, as the trait was added later.
While it was explicitly expressed in season 2 that Data can not use contractions, the fact that they did established this character trait means it could be a valid mistake since the trait is meant to show Data could never use contractions since his creation, not that he suddenly developed it some 30-odd years later. Although it would probably be best to submit it as a mistake in season 2 when it's mentioned that it contradicts what was established or at least make one character mistake for "all of season 1" than list every individual time it happened.
Other mistake: As Crusher enters the police station, Data says "Hiya, Doc. What's cookin?" He's supposed to be incapable of using contractions.