Revealing mistakes

When Sheldon is being driven to school in his mom's station wagon, the ignition switch is clearly in the off position.

Factual errors

When 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, a simple Google search will state that Purell was invented in 1988, one year before the statement would have been made.