Eagle-eyed horror buffs might catch a nifty visual joke in the dramedy Silver Linings Playbook when it hits theaters Nov. 21. During a scene in which costars Bradley Cooper and Jennifer Lawrence get into an argument outside a movie theater, the title on the marquee reads The Midnight Meat Train. What is that? Well, it's a gruesome 2008 flick about a cleaver-wielding subway serial killer ... starring none other than Bradley Cooper as the man obsessed with stopping him. Linings director David O. Russell explains, ''I wanted a horror film up there, and with this very heavy scene happening underneath it, it was just a fun inside thing for us on the set.''