Deepfake showing Tom Holland, Robert Downey Jr. shows how seamless the tech can be

A new video is proving you can’t believe anything you see on the internet once again.

The viral video that has more than 2.7 million views since posting on Friday shows Tom Holland and Robert Downey Jr. starring as Marty McFly and Doc Brown, despite never being in the movie “Back to the Future."

Holland, who is only 23 years old, wasn’t even born yet when the “Back to the Future” series was first released in 1985.

But that doesn't stop him appearing in the short clip -- his face overlayed on Michael J. Fox's, while Downey takes the place of Christoper Lloyd, CNET reported.

But it’s only their faces. The original actors’ voices remain in the clip.

The clip, while fun to imagine the recasting, shows how good deepfake technology has become, leaving some concerned that what voters see this political season is far from reality.

And deepfakes are not new, with CNN investigating the technology more than a year ago.

University of Southern California professor Hao Li called the practice of deepfakes scary, in an interview with the BBC.

“We are already at the point where you can’t tell the difference between deepfakes and the real thing,” Li said, despite developing a deepfake program.

He said the software was not designed to trick anyone and will be sold only to businesses. It digitally maps a person's face then swaps it with that of another, the BBC reported.

Facebook has banned deepfakes, with officials saying they could manipulate people, the BBC reported.

Specifically, Facebook announced earlier this year that it would ban videos that are "edited or synthesized," USA Today reported. But it will still permit parody and satire.

The company is also trying to find a way to use artificial intelligence to detect deepfakes, according to USA Today.