The origin of Sheldon's catchphrase "Bazinga!" is established.
The comic book that the cashier is reading at the King Kong Comics store is "The Flash" #186, where Flash's skeleton is discovered by two boys. It is marked for twelve cents. It was published March, 1969.
The "Vanity Card" (#604) broadcast as part of this episode (and still contained on the DVD/Blu-ray release) consists of one word, written in Cyrillic characters which, in Roman letters would read something like, 'vinovniy'. Beyond the English meaning, which is "guilty", and the fact that it's written in Cyrillic, viewers can make their own conclusions as to its significance.