Then you should read it! And, you know, see a production, specifically Branagh's, but in my experience it's easier to follow if you've read it first.

The similarities are really pretty general, though, mostly using tropes from storytelling in general rather than specific Hamlet stuff. The only bits that put me specifically in mind of Hamlet are Cal's lines about the king being dead (this sounds like a deliberate reference to me, with the part of about the joker indicating the difference between Cal's being manipulated and Hamlet's doing the manipulating) and the scene with Cal seeing Reed. Which, the idea of Hamlet tripping on acid gives me joy like I can't even say. <3