One of Stan's hats was The Man with the The Yellow Hat from Curious George.
The shop next to the MailBox CopyStore is P. Falk & Co., a reference to the late actor Peter Falk complete with his catchphrase "Just one more thing".
Roger alludes to "Kaiser Soze", a villain who is a fiction-within-a-fiction from the 1995 film The Usual Suspects when he gives "Wheels" he full name of "Squirt "Wheels" Cinnabon" based on items left on top of a cabinet.
When Steve and Roger discover the satchel, they open it and it glows back at them. This a reference to the film Pulp Fiction. In the film, there is a briefcase carrying unknown contents that glows at it's over-looker.