Discussing whether flashbacks are a good idea with writers is about as easy as trying to choose your favorite Star Wars movie. There really isn’t one definitive answer. We just want to say that avoiding flashbacks more often than not is probably a good rule of thumb for all screenwriters.
In some respects, writing your third act is the easiest part of your script. You’ve done all the exposition, the audience has fallen in love with your characters, and the only thing left is explaining how the story resolves. Well, maybe it’s not that easy. You do have to answer all, or at least most, of the questions you’ve raised, let the audience know what happens to each of the characters, tie up every loose end and make it all really, really exciting.