Sheldon's sister teases him in church about his "balls". Sheldon replies that his testicles "haven't descended yet" because he's only nine. But, boys' testicles descend at birth. It is a strange myth which many people seem to believe, that testicles somehow "descend" at puberty. The reality is, even little boys have descended testicles. As a boy genius, Sheldon should know that about himself.
Sheldon states that he would not touch his brother's hand until 17 years later, "thanks to the invention of Purell". This implies that it was invented in 2006 based on the plot taking place in 1989. However, Purell was invented in 1988 and made available to consumers in 1997. Even then, alcohol wipes had been available since before Sheldon was born. His claim about Purell and disinfecting his hands in general is just straight-up false.
When Sheldon is being driven to school in his mom's station wagon, the ignition switch is clearly in the "off" position.
When Sheldon walks in to a near-empty classroom on his first day in High School, he sees music teacher Ms Fenley playing the opening melody of Mozart's Sonata No.11 in A K.331 on the Cello. She is, correctly, playing it in the key of A, but for some reason does not play the last note (B) of the fourth bar to end the phrase. Sheldon, as yet unseen by the teacher, sits down at the piano and plays the melody along with the teacher as she repeats the same tune, and he also leaves off the last B. She asks him if he knows the sonata, and he replies that he doesn't play piano. Later, Ms Fenley tests Sheldon by playing some chords, which he then identifies without looking at the keyboard: G minor, F, E-flat, C minor. She comments that he has perfect pitch, while the test she uses is more appropriate for identifying the skill of "relative pitch". All of this, however, is overshadowed by the question of 1) how Sheldon could immediately choose the right key on which to start the Sonata melody, and 2) how he would know the names of the chords without prior musical study.
However, it is possible that Sheldon read and listened to musical pieces and knows about the tuning of a piano without having studied it.
However, it is possible that Sheldon read and listened to musical pieces and knows about the tuning of a piano without having studied it.
The poster of W. Axl Rose seen in Georgie's bedroom is from a 1991 Guns N' Roses concert. This episode is set in 1989.
There are no mountains in east Texas (as shown in the intro).