2. Maybe as you just watched that you thought “whoa, did I just see Christopher Reeve?”
3. Look at the gif again. At the very beginning you can see that the lips and nose are thinner:
According to a redditor’s comment, an editor on the film says no one has admitted to adding Reeve’s face. But it’s kind of hard to deny that you see something.
7. Maybe it’s the lighting.
9. Whatever the answer is, it’s nice to kind of see you again old friend!