It happens to every writer: you’re writing along when suddenly you need to go back and change some fact or detail.
Because if you don’t fix it, the story won’t make sense. Should you stop writing at that moment to go fix it?
Nope. That could kill your momentum.
Here’s a better idea. It’s called a retcon, and comic book writers have been using it for decades.
Retcon is short for “retroactive continuity” and it means that you’re stating a new fact that changes what’s come before.
In other words, you’re changing the past.
This is a term I first encountered in the massively entertaining and informative book Writing for Comics with Peter David. (Mr. David, by the way, has an impressive list of comic writing credits, including Spider-Man, Wolverine, Supergirl, Hulk, Star Trek, and tons of others. He knows what he’s talking about.)