Apparently there's a rights issue with MODOK...
N: Cool. Were there any villains from Cap’s rogues gallery that you wanted to include early on but just couldn’t fit them in?
SM: That is a secret, backdoor question to who’s in it!!!!
N: No, no! [laughs] there’s so many!
CM: No, there are the favorites I’m always trying to wedge in, but the problem is you can’t wedge in a giant, flying head. It’s not like MODOK can pop up in one scene. But, I think you’ve seen in the casting announcements that a couple a snuck in.
N: There’s definitely been a couple. Personally, I’m hoping Peter Dinklage is going to be MODOK in Days of Future Past but that’s just me.
CM: There’s a rights issue there, somehow.
I don't understand how there could be a rights issue with MODOK. He first appeared in Tales of Suspense, is historically a Captain America and Avengers villain, and is primarily associated with AIM. There's no way Fox should have any rights to MODOK with their FF and X-Men license. If they have MODOK I can only imagine what other random **** they have.
EDIT: Oh wait, it looks like he's saying there's a rights issue with FOX using Dinklage as MODOK in DOFP. Alright, that makes more sense.
2014 - Captain America: The Winter Soldier | The Amazing Spider-Man 2 | X-Men: Days of Future Past | Guardians of the Galaxy
2015 - Avengers: Age of Ultron | The Fantastic Four | Ant-Man
2016 - Captain America 3 | Batman vs. Superman | X-Men: Apocalypse | The Amazing Spider-Man 3 | Doctor Strange
TV - Agents of S.H.I.E.L.D. | Agent Carter | Daredevil | Luke Cage | Iron Fist | Jessica Jones | The Defenders
TV - Arrow | The Flash | Gotham | Constantine | iZOMBIE