Typically, when a movie comes out, the finished product leaves a lot of content on the cutting room floor. The directors are usually the ones who regret their cut content, which is why Director's Cuts are so popular. They allow the public to see the director's original vision.
Of course, there are sometimes scenes the director leaves in the movie that they probably shouldn't have. It happens from time to time, but when a bad scene makes it into a film, it can derail the whole thing. Mismanaged editing can result in incongruous narratives and messed up character development, so editing is important.
Of course, everyone has regrets, and while the director likely gave a scene the okay before it left editing, they sometimes come to regret their decision. Stanley Kubrick famously had the final scene of The Shining literally cut from the reels and mailed back to him.
Had he not done that, odds are, he would have regretted keeping the scene in the movie. More often than not though, regret comes from a scene that is near-universally hated from a finished cut. When that happens, you can bet the director wished they pulled a Kubrick at the eleventh hour.
Jonathan is a graphic artist, illustrator, writer, and game designer. Jonathan retired from the U.S. Army in 2017 and enjoys researching and writing about history, science, theology, and many other subjects. He writes for ScreenRant, CBR, NerdBastards, Listverse, Ranker, WhatCulture, and many other sites online. You can check out his latest on Twitter: @TalkingBull or on his blog: jonathanhkantor.com