In “Mad Max: Fury Road,” vehicles scream through a canyon and launch past one another as our heroes desperately stage their escape. Though the shots are seamless and the action appears to take place in real time, many of these cars and trucks were never in the same frame at the same time. In some shots, the cars weren’t even moving. They were jiggled and the fast-moving background was green-screened behind them.

Welcome to the world of invisible visual effects, where not even the pros can tell you when and where the sleight of hand begins and ends. These days it’s not just the audacious explosions and massive flying spaceships that become the spectacle for an audience — vfx are used to stage core environments, backgrounds and landscapes.

In fact, effects are so ubiquitous, even in smaller films, that judging their success around awards season can be problematic, even for the experts.

“The storms we created for ‘Mad Max’ are probably the more obvious things we did for the film, and we worked very hard on them,” explains vfx supervisor Andrew Jackson. “But the things we were able to do with making it look like there were several trucks in a shot that weren’t really there together, those things were important in terms of the feeling of the film.”

Jackson is also quick to admit he’s not always sure what’s been done to a film, unless he’s seen a before-and-after reel.

“Things have gotten so good, you really wouldn’t know, and if you’re seeing the film in a theater those shots are going by pretty fast,” adds Jackson. “You really want to be able to study the work that was done.”

Jackson, who has also worked on “300” and “Happy Feet 2,” isn’t the only vfx supervisor to acknowledge it’s hard to know where the practical effects end and the digital ones begin.

“I think we’ve reached the point where we need before-and-after reels so that we know what was done in a shot, and I think we’ve been there for a while,” says John Knoll, who has more than 29 years’ experience on films such as “The Abyss.” Knoll is also an Academy Award-winner for his work on “Pirates of the Caribbean: Dead Man’s Chest,” leads the vfx branch of the Motion Picture Academy’s board of governors and is the chief creative officer of ILM. “The technology and techniques we use mean that it’s very likely you would not know exactly what was done unless you’d worked on it yourself.”

The Academy allows for a brief introduction of those films being presented for consideration at its vfx bake-off followed by a reel of effects shots.

The Visual Effects Society takes a different approach to its awards season. In addition to submitting a section of work as it was seen in its theatrical or broadcast release, “it is mandatory to include a before-and-after reel that addresses the material submitted only… so no new work can be presented in the before-and-afters,” writes VES member Jeff Okun in an email.

Okun, who was involved in establishing the rules for the VES Awards, also thinks vfx work has progressed to a point where even pros need to be educated about the techniques used in a shot.

Ken Ralston, a five time Academy Award-winner and veteran vfx supervisor known for his work on “Star Wars” and “Forrest Gump,” believes the issues don’t end once films emerge from consideration by the vfx branch.

“It becomes a bigger problem once you get into the general membership of the Academy because the tools are changing so rapidly and what we’re able to do is changing so often,” explains Ralston. “If we’re unsure about the complete extent of what’s been done to a shot, it’s not fair to expect someone who doesn’t have the background that I have to be able to see everything that’s been done.”

Ralston is reluctant to say Academy members should be required to view before-and-after reels before voting on vfx work, but he does believe detailed information about what was done on a film should be made easily available to voters.

Before-and-after reels aren’t just an education for those who work outside of the vfx realm. Often, there’s a huge educational bump for those who work with vfx as well. Dadi Einarsson, a vfx supervisor on “Everest” who also worked on “Gravity” and “Sherlock,” looks to this footage to get ideas for what he might attempt on his next project.

“I love to see other people’s before-and-after reels because you get a sense of what they did and how they did it,” says Einarsson,  also known for TV miniseries “Dinotopia.” “Honestly, it’s not always obvious what was done to a shot because we had to build an entire base camp because (the weather made it) impossible to shoot there.”