How do you solve a problem like your action-movie leading man being nearly 80 and presumably no longer able to get under those rolling boulders quite as he once did? For the new 1960s-set Indiana Jones movie, once again starring Harrison Ford as the ageing adventurer and disturber of ancient tombs, there are rumours that the answer might just be time travel.

Fans this week have been all over suggestions that Indy will head back to Roman times, as suggested by recent set pictures, though of course he might just be on the 1960s Hollywood set of a swords-and-sandals epic. Then again, there was also that video, published in June, suggesting the archaeologist will be facing off once again against the Nazis, despite the second world war having finished more than two decades earlier.

Could Indy be searching for a new mysterious MacGuffin that allows journeys into the past in James Mangold’s film? This would both explain the apparent scenes from two wildly different eras, and give the director the opportunity to present our hero meeting a younger, digitally de-aged version of himself.

And yet quite how Mangold would present the transition from the near-octogenarian Ford to a version played by the actor via motion-capture “ghosting” (otherwise, what’s the point?) remains to be seen. It’s certainly not beyond the realms of possibility: we’ve seen actors brought back to life (Peter Cushing as Grand Moff Tarkin in Star Wars: Rogue One) and even movies in which the leading players have been digitally de-aged for most of the run time (The Irishman). Mangold could even kill off Indy Prime, while keeping young Indy for future episodes, though one has to assume even the famously self-confident Ford will be up for retiring the role at some stage.

Another set photo emerged earlier in June showing a stuntman on the set of Indy 5 who appeared to be wearing a Harrison Ford mask. Perhaps this is a new method of digitally de-ageing that we haven’t yet come across. Or maybe somebody somewhere is having a laugh with the paparazzi who keep capturing this stuff. Presumably if successful mo-cap impersonation could be achieved by pulling on a crap rendition of someone else’s face, we’d all be able to sit through the famous lost Bruce Lee movie Game of Death (which was completed, terribly, after the martial-arts legend’s death) without having to reach for the sick bag.

Frankly, whatever Mangold is up to, it smacks a bit of desperation. Time travel just about worked as a narrative switcheroo in 2009’s Star Trek, despite the protests of long-term fans of the space saga, because it’s a staple of science fiction. And the supernatural elements of the early Indiana Jones movies worked because the Nazis really were obsessed with occult objects. The idea that Indy and his rivals from the Third Reich might be competing to chase down antiquities such as the Ark of the Covenant and the Holy Grail made total sense for period pieces set in the classic pulp-fantasy era.

But nobody really liked the most recent Indiana Jones movie, 2008’s Kingdom of the Crystal Skull – featuring a relatively youthful 66-year-old Ford – partly because the Soviet Union was not exactly known for being obsessed with aliens (as Cate Blanchett’s nefarious Irina Spalko patently is). Why try the trick again 13 years later when the obvious answer is to recast the role or retire the franchise?

Mangold himself argues that naysayers have yet to see the final cut of Indy 5. “I understand wariness, I live it. I don’t know if I’ll make you happy but my team and I will knock ourselves out trying to make something good,” he wrote on Twitter in June. “We admire the craft of the originals. I hope when you see real images, they’ll look better to you than paparazzi shots from bushes. Maybe, just maybe, I won’t let you down. I cherish old Hollywood pictures. Give me a little air to make the film. Then make your judgements, okay?”

It’s a fair point. And perhaps, in 2023, by the power of digital wizardry (alongside time travel and a stonking good story) we might yet see a fifth Indiana Jones movie that stands proudly in the pantheon. Failing that, it had better be a really clever mask.