Superman‘s opening scene has a behind-the-scenes secret that changes how you look at the first segment of the DCU movie. As both the start of the DC Universe timeline and the superhero movie with the highest box office of 2025, Superman is an important film in many ways.

As such, the release of the behind-the-scenes Superman movie documentary Adventures in the Making of Superman is all the more fascinating, since it provides a series of interesting insights about the film. One such insight makes the first moments of the 2025 DC movie all the more noteworthy, by revealing an unforgettable detail about this part of its story.

Superman’s Opening Looks Different Thanks To The Behind-The-Scenes Documentary On The Movie

Superman‘s opening – wherein we’re introduced to the hero and his world via being shown him lying in the snow – is one of the most important parts of the DCU movie. Not only does it kickstart the plot in a major and dramatic way, it also provides an early look at the more vulnerable side of the hero.

Superman being rescued by Krypto after whistling for the dog also provides a very early introduction to the canine character. Indeed, the scene of Krypto coming to ostensibly save Superman – only to wrestle with him a little – does a solid job of showing off the pooch’s chaotic nature right off the bat, and the duo’s complicated bond.

However, the DCU’s recently released Adventures in the Making of Superman sheds a little more light on what this scene originally looked like. The documentary shows the filming of this scene, complete with James Gunn giving David Corenswet direction, and shows that there was no stand-in for Krypto here, with Corenswet simply kicking around to replicate the fictional dog.

While this doesn’t ruin the scene by any means, it certainly changes how viewing it again feels, thanks to the knowledge that this segment of the movie is the actor by himself seemingly reacting to nothing. In a sense, though, this does make the scene more entertaining after watching the documentary, since viewers then know how the “real” scene unfolded.

Why Krypto Being Fully Added Into The Superman Scene After Filming Makes Sense

The decision to film the Superman opening in this way is interesting, since the years have established figures like Krypto often have some form of stand-in in these kinds of scenes. Though it makes sense a real dog wasn’t grappling with Corenswet, it’s easy to imagine the scene was filmed by something or someone external ᴀssisting the actor.

That said, looking at the scene with the context from Adventures in the Making of Superman, it makes sense this choice was made. Ultimately, anything or anyone who would be used in that scene to help Corenswet’s movements look as though they were from being pulled around by another party would have needed to be edited out later.

This would have needlessly complicated the sequence, and added extra onto the film’s budget somewhat unnecessarily also. As such, having nothing serve as a stand-in for Krypto in this scene does seem the most straightforward approach, even if it’s one that provides an interesting behind-the-scenes secret behind the Superman opening.

Similarly, with David Corenswet being a clearly proficient actor, it stands to reason there was less of a need to add an external source for him to react to. Indeed, looking back at this segment of the film with this all in mind does further prove how right the DCU seems to have been with its Superman casting overall.

The Superman Opening Scene Being All David Corenswet Actually Makes It More Impressive

While it’s worth adding the caveat that Superman as a story does not live and die based on how convincingly audiences felt David Corenswet reacted to Krypto in this introductory scene, it’s also a crucial point of the story. If audiences had found elements of Corenswet’s performance jarring this early, it could have sabotaged the rest of the film.

Instead, it’s borderline impossible to tell that the actor is reacting to thin air in this scene, which speaks as an early testament to how promising Corenswet is as the Superman of a world that will no doubt feature a range of CGI allies and enemies. That said, this isn’t solely impressive in terms of the DCU’s Superman actor alone.

VFX teams are often given some building blocks to work with for characters like Krypto in these scenes, be that though someone in a mocap suit or a stand-in prop playing the role. Instead, the team involved here were able to make Krypto react perfectly to Corenswet’s motions seemingly from total scratch, which is a testament to their talents.

Altogether, seeing the effort that goes into making scenes like the Superman opening sequence work – both from the film’s on-screen talent, and its off-screen talent – helps to make it feel even more special on some levels. That said, it may also make it a little harder to not crack a smile at Superman‘s opening when giving the film a rewatch.