Other mistake: As Young Sheldon is a prequel series to Big Bang Theory, this episode is at odds with episode 2-13 of Big Bang Theory, "The Friendship Algorithm," in which Sheldon is unfamiliar with books like "How to Make Friends and Influence People," which he reads in this episode of Young Sheldon, produced nine years later but taking place twenty years earlier.
Factual error: The commentary suggests that Sheldon had the correct solution to problem 1 and merely lost points on the quiz because he didn't show his work. In reality he did the first problem incorrectly. Taking the derivative of (x+2) ^2+ (y+1) ^2 = 13 with respect to x yields: 2* (x+2) +2* (y+1) * (dy/dx) = 0 which implies that: dy/dx = - (x+2) / (y+1) and at the point (0,2) this means that the slope dy/dx is actually equal to - (2/3), not 2/3. It is correct that when using the form y=mx+b at the point 0,2 reveals that 2=m*0+b, or that b=2. So the correct equation for the tangent line is y = - (2/3) x + 2, not y = (2/3) x + 2 as shown in the episode. (00:13:55)
Factual error: In this episode we see George throwing a ball against his bedroom wall. On the wall is a picture of Axl Rose wearing shorts in the pattern of the USA flag. This photo is from the Guns N' Roses appearance at Rock In Rio 2 festival in Jan 1991. The show is set in 1989. 2 years prior to the photo the poster is made from is taken.
Plot hole: Near the start we see Sheldon using physics to try and take down Tam. This completely goes against all of Sheldon's phobias about touching people, especially socks. Even before this episode he has shown his displeasure at the thought of touching people. (00:05:00)
Continuity mistake: When Sheldon and Missy are sitting at the table, Missy puts a paper in the basket in front of her. A couple of shots later when she says "sounds right" the paper has disappeared. In the next shot it reappears, in a different position than it was before.