“There is no Nathan Fillion cameo and there never was a Nathan Fillion cameo.
As it turns out, Nathan Fillion was never actually going to appear in-person in Guardians of the Galaxy Vol. 2 after all.
Much to the excitement of Marvel fans everywhere, Guardians of the Galaxy Vol. 2 is packed to the brim with unexpected Easter eggs and comic book references.
In those posters, and only in those posters, Nathan Fillion was Simon Williams.”