What are the prequel references in the film? I counted a few, but don’t almost none are direct and some might not even be intentional.

MILD SPOILERS:

Lor San Tekka mentions bringing balance to the force (was this a concept before the PT?). There’s also the speculation going around that his first line is a shot at the PT (“This will begin to make things right”) which is entirely possible
Kylo Ren asks Hux if they should be using a clone army instead of the brainwashed recruits they have (feel like this was put in so those expecting the stormtroopers to be clones wouldn’t be confused)
Maz mentions the Sith (a word that has been a part of Star Wars since the original, but only spoken on film before in the PT)
Ewan McGregor provides a voice-over for Rey’s vision (probably the only direct acknowledgement of the existence of the PT honestly)
This is conjecture, but I feel like Kylo’s hair-do might be purposefully reminiscent of Anakin’s in ROTS (in-universe as well as behind the scenes)