When Data has finished waxing Timothy's hair, just before he turns Timothy to show him the new hairstyle, there is a visible tuft from the boy's head on his right side (our left). As Data stands up to turn the chair, the tuft of hair has been waxed down properly.
Near the end, when Worf says "Wave front intensity has increased by a factor of 10. Contact in 30 seconds.", the view switches to a forward shot of the helm and main viewscreen as seen from Worf's station. Data can be seen in the left hand seat (it's obviously Data from the bright white skin). Data, however, has walked away from his position and is seen at the science station to Worf's right side throughout this part of the scene.
Timothy falls asleep while he and Data are painting, and Data picks him up and moves him to the couch. When Data picks him up, he is holding the brush and palette, but, in the next shot, when Data puts him on the couch, they are gone.
When Timothy and Data are comparing their perceptions of their respective desserts in Ten Forward, Data lists one of the components of his beverage as carbon dioxide. However, the liquid in his glass does not appear to be carbonated. An android would get this right.
However, carbonated drinks don't always have visible bubbles to reveal the carbonation. Moreover, many non-carbonated drinks contain low concentrations of naturally produced carbon dioxide. A prime example is the natural beers known in the UK as 'real ales'. They do contain carbon dioxide (produced by fermentation, not artificial carbonation) but are not obviously 'fizzy' and have few or no obvious bubbles.
When Data and Geordi are in Engineering, they are looking at a screen when Data is saying that 83 percent of the data is lost. Moments later, you get a shot of Data and Geordi looking at the computer screen. Somehow their movements are not in sync with the mirror image of that screen.
Timothy tells Data that the crew of the Vico were talking about increasing shield power before the ship was destroyed. This discussion took place on the bridge, which was exposed to space. It is unlikely Timothy would have heard this discussion unless he were on the bridge or in engineering.
Timothy is given his own quarters aboard the Enterprise. A young boy who had just been through a traumatic event would be put into a form of foster care, not simply left to his own devices.
Data refers to Lieutenant Commander La Forge as "Lieutenant La Forge". Lieutenant Commander may be shortened to Commander, but not Lieutenant.
After Data yanks Timothy out from under the rubble where he's trapped and carries him out to the open corridor, he calls out "Energize!" before touching his communicator pin.
Data tells Timothy that he is not offended by the boy's attempts to emulate him, as he has been told, "imitation is the highest form of flattery." This is a common shortening and gross distortion of the original meaning of the phrase. The full phrase, attributed to Oscar Wilde, is, "Imitation is the sincerest form of flattery that mediocrity can pay to greatness." It is an indictment of imitation, and mockery of those who practice it, not a sincere belief that it is a compliment. While it's possible that data may have heard the common shortened version, it is unlikely that a curious and knowledgeable being such as he would be unaware of the phrase's full meaning.