Corrected entry: At the end of this episode everyone gets up from being stunned a second time. When they go to check their stations and leave, does no one notice Star Fleet's time? They have been knocked out for 30 seconds and yet Star Fleet says it's two days later. Someone should be drilling Data again.
Corrected entry: When Picard returns to the Paxxan planet, Data begins to replay the incidents that led to the "lost day". During the narrative that Data gives, he explains that Captain Picard asked the Paxxan representative, who is using Counselor Troi's body to communicate, who (meaning what species) they belonged to. The alien possessing counselor Troi never answers this question. Instead the alien informs Picard that because the Enterprise crew is aware of the Paxxans (who are xenophobes and isolationists) and the ship and its occupants must be destroyed. Picard asks the alien to allow the Enterprise safe passage through their space, and to erase the entire crew's memory of the incident, however the Paxxan representative says that Data is immune to their technology to erase memories (which would have been required in order for the plan to work). Captain Picard says to Data, "You will conceal your knowledge of the Paxxans for as long as you exist". However the species was never identified. This happens in the last 6 minutes of the episode.
Correction: As I recall, it was Data who explained to Picard that the aliens were Paxxans and xenophobes after it was discovered that Data's "cover story" about the missing day was untrue. Picard's question to the alien about who they are, could be interpreted a number of ways, and not just to identify what their species is called.
Correction: Data explicitly states when explaining the earlier attempt that he modified the ship's chronometer so that the crew would not know time had passed. Data (with the crew's help) corrected all of the "clues" the crew found in the previous attempt. It would be a simple task for data to adjust the chronometer to run a tiny fraction faster for a short period so that it would catch up with the actual time without the crew noticing.