Pretty Little Liars is kind of my guilty pleasure; so crazy and so good. The directors and writers are such film lovers, and they've referenced or shown a couple of films along the way, not least of all Alfred Hitchcock tributes. Being the film fanatic and fangirl that I am, I've been loving the intersection between the two.
Director Norman Buckley talks about the series' literary and film references here.
Switch to notes view for elaboration on the references! Some descriptions are taken from the PLL Wiki.
Edit: Whoa I didn't expect there to be so many films, but I really had fun compiling this!