Giving more visibility to this question, as it's something I'd very much like to know as well! I would have thought passing references/nods such as yours would be okay, but it's better to be sure... I intend to slip some reference characters in the audience to some fights, similar to what you do here, but if it proves to be a legal problem, I'll have to reconsider it as well. (I can even ask right here: would anyone here want a character from their work featured in that way, as a general question, and in the case of my idea of appearing in an audience in Honey?)
Though to be honest, seeing how removed yours are, I think they can safely be considered as reference and still work for people with a keen eye... though I hadn't even recognized Manny, even though I'm a big Grim Fandango fan. (now that I know, though, I can see him all right, so no problem here)
And in other news, I'm getting back to the fighting stuff now, so I'll have more 2D animation to show as well, hopefully soon.