Picard tells Riker they're in Schoolroom 8; however, when Picard returns, the screen shows that they are in Classroom 7.
The ambiguities of the Stardate calendar allow Molly O'Brien to be about 4 years old, even though it's only been one year of "screen time" since she was born in Disaster (1991).
The adult Picard has blue eyes and a prominent dimple in his chin; his "younger" self has brown eyes and no dimple.
The four shuttle crew members are seated when beamed aboard the Enterprise and materialize standing up.
By this time in the present, archeologists have been discouraged from permanently removing artifacts from the country of dig sites, some have even been threatened with legal action. Yet at the time this story takes place, Picard has taken some historically significant items back to the ship with him with no repercussions.
O'Brien was a junior lieutenant in previous episodes and now he has a half pip indicating that he is a chief petty officer. There is no explanation made for this very large reduction in rank throughout the series.
Picard has an adult-sized artificial heart that somehow seems to fit just fine in his younger version's self, and it does not cause him any discomfort either. It could not have been changed to a smaller size since his uniform did not change size either. However, we do not know the size of the artificial heart: it may have been smaller than a real heart, allowing it to fit into a younger chest cavity.
When the Ferengi transport aboard the Enterprise bridge, the beam is of Ferengi origin rather than what it would be from the stolen Klingon ships they use to attack the Enterprise; however, the DaiMon stated they had "made repairs," so a new Ferengi model transporter would be a likely repair.
When young Keiko O'Brien gets coffee for herself and Miles, his black coffee starts out in her right hand, but when she walks over to hand it to him, it's in her left hand.
When the shuttlecraft encounters the energy field, it is supposedly subjected to turbulence. The actors shake accordingly, but the camera operators forget to shake the camera to enhance the effect. It makes the actors appear to have uncontrolled spasms.
When the boy Picard sits at the classroom computer devising his plan to retake the ship, he shows to the girl Ro and the girl Guinan the path they need to take to get to Engineering. He shows them that they will have to travel through a Jefferies tube and then cross an open corridor to get to their destination; however, the diagram the computer displays is clearly of a slice of the saucer section, port side. Engineering is in the secondary hull, below the saucer section, some 20-odd decks below where the children are.
One Ferengi beams onto the bridge about twenty feet away from Worf, who manages to miss him with his phaser. This does not seem like good marksmanship, particularly for the chief of ship's security.
No Ferengi questions young Picard or young Ensign Ro wearing a Starfleet uniform, or with young Picard bearing captain insignia.
After the younger version of Picard is brought to the classroom by a Ferengi, younger Ro suggests flooding the ship with anesthezine gas, but Picard says that has been locked out of all command functions. How does he know? He wasn't on the bridge when Riker gave that order.
During the battle, Data states that the sensors are offline, yet a few seconds later, sensors detect the Ferengi boarding the ship.