When Wolowitz finds the stack of checks in Sheldon's drawer, and wonders why he hasn't cashed them, Sheldon explains that he's saving them to purchase items that have yet to be invented and doesn't trust banks. But just keeping them in his drawer doesn't do anything, because checks are voided after a set period of time (usually between six months and a year) and they would eventually become worthless.
When the guys sit in the living room searching comic books to be signed by Stan Lee, Sheldon says "... will set me apart from the hoi polloi of comic fandom". "Hoi polloi" is Greek for "the majority", making the usage of "the" before it redundant. This is especially important as Sheldon is depicted as being very accurate about foreign language terms; he wouldn't have made a mistake like that.
Raj wants to ask Stan Lee about his alliteration in character names and Howard tells him not to because it will annoy him. No wonder, as he has stated that this quirk is because he has a bad memory and it made it easy to remember. Surely a fanboy would know that.
Sheldon states that he doesn't trust banks, though in two previous episodes, he referenced his use of them. First, in Season Two's "The Financial Permeability", he mentions he has a "small savings account". Then, in Season Three's "The Jiminy Conjecture", he retrieves his "Flash" comic book from a safe deposit box, which he would have had to rent from a bank.
Penny is shown to have identified Sheldon as the person driving her car when it ran a red light on camera. In California, photos are taken of the driver. If the driver cannot be identified, the owner is sent a ticket known as a "snitch ticket" that can be ignored.