A seemingly innocuous dig at his roommate is actually plagued with timeline errors.
This is because in The Staircase Implementation, the 22nd episode of season three, a flashback scene shows Leonard interviewing for the spare room in Sheldon’s apartment.
The year of the roommate interview and their first meeting was in 2003.
However, Star Trek: Nemesis premiered in the USA in 2002, a whole year before Leonard and Sheldon had supposedly first met.
Big Bang Theory is available to stream on Netflix UK now.