Missing enemies

[King80]

Yea so I finished the game last night and I was happy about that but something didn't feel right so I  looked back at some of the trailers and screenshots before the game was released and I noticed that some things were missing. I noticed that I didn't fight the gingers a second time nor did I even fight the vampire kids, hippies, the crab people or giant craig. I thought it was because I was only able to fight them in the post-game but after playing around for a couple more hours and searching the whole map I still can't find them so I was wondering if I have to talk to someone to trigger those events or their just DLC's that we're going to get later or they were just there to promote the game?