Deadpool

Among the many little easter eggs and jokes in the opening title credits scene in Deadpool is a little keychain.  The keychain is of two figues doing the deed.  Apparently the hired goons Deadpool is disposing of had a sense of humor too.

http://www.artofthetitle.com/title/deadpool/  Has a thorough breakdown of the opening titles.

Frasier

From season 11 episode 17.  This is probably the only visible keychain in the entire run of the show. Frasier has a patient with kleptomania in order to feel more excitement in her life. At the end credits scene Niles steals one of Frasier's sherry glasses and Frasier steals Niles' car keys.  As they exchange their stolen items Niles' Mercedes keychain is seen, which is appropriate since he drives a Mercedes.