When Howard and Raj talk about girls who have rejected them, Howard refers to Marcy Grossman. She was mentioned in The Killer Robot Instability (2009) as the girl to whom he sang 'My Girl' with her name in the lyrics during a school talent show, but she simply approached him afterwards and spit in his hair.
The rare comic book that Bernadette is trying to replace is "The Dark Knight Returns", the famous Batman story written by Frank Miller.
Captain Sweatpants' last appearance on the show, and also the only episode in which he has lines.
This is the penultimate time that the Cheesecake Factory is visited. It appears one more time in a flashback in season 11, and is visited one last time in the penultimate episode, The Change Constant (2019).