In the beginning episodes of Puella Magi Madoka Magica, Kyubey offers the teenage girls in the series the chance to have a wish come true in exchange for becoming a magical girl, and moreover seems to imply that any wish can be made possible.
However, in the last episode, Kyubey tells Madoka:
Since you're now the central point of karmic destiny from numerous different timelines, no matter how enormous the wish, you will likely be able to make it come true.
This of course seems to imply that with some other magical girls, some wishes are too "enormous" to come true. But this seems to contradict Kyubey's earlier words, and this doesn't really seem to be a point of deception either.
Given this, are some wishes actually impossible for some magical girls, or is there perhaps actually no inconsistency here?
EDIT: I've only watched the anime series, and while the first two films sound a lot like an adaptation of the contents of the anime, I don't know much about the Rebellion film. If this is of any "importance", I am referring to whether or not all wishes are possible prior to the aftermath of Madoka's final decision to remove all witches in time and space from coming into being.