‘Don’t blowtorch my head!’ The Home Alone recreation that nearly fried James Acaster and Guz Khan

In a grey corner of Borehamwood in deepest Hertfordshire, a film set is coming alive with one of Christmas’s most magical traditions: cartoonish ultraviolence. Bags of unopened marbles lie ready to shatter someone’s vertebrae. A blowtorch is rigged to incinerate the first person to step through a doorway. Piles of dented paint tins are freshly bent out of shape from being swung into torsos. And everywhere there is tinsel, fake snow and twinkling fairy lights. ‘Tis the season to be jolly, all right – jolly badly hurt.

This is the set of a new show celebrating one of the all-time classic Christmas movies. The Unofficial Science of Home Alone is a look at what would happen if you actually subjected someone to the film’s booby traps. To do so, they’ve created an exact recreation of the set and the pranks – with a couple of exceptions. First (presumably for legal reasons) the staircase is lined with photos of a family that looks like (but is not) the McCallisters, including a fake Macaulay Culkin whose blazer and dodgy bow-tie make him a closer match to a young Niles Crane. Also, as far as we can remember, the original movie did not star comedians James Acaster and Guz Khan as the Wet Bandits.

“Home Alone is one of my favourite Christmas films, easy,” says Acaster, who is getting to live out the dream of many a childhood fan of the movie: taking part in it. Although, generally, most would prefer to be setting the traps, rather than risk having them inflict excruciating pain upon their own person.

“Yeah,” adds Acaster, “but once you grow up, you realise the pranks would actually kill people, which stops you wanting to do them as much. You hit someone with a paint tin and they will die. Then you’ve got to live with that for the rest of your life. So it became more interesting to think about whether you could actually survive any of the pranks, and how that might work.”

Just to add a bit of spice, they’ve decided to opt for five of the movie’s most extreme bits of slapstick brutality. They’ll recreate the scenes in which Joe Pesci (Harry) has his skull set on fire and burns his hand on a red-hot doorknob, as well as the ones where Daniel Stern (Marv) has his face stoved in by a swinging paint can and the Home Alone 2 moment when he’s electrocuted to skeleton-revealing levels by a sink that’s rigged to a generator. Then, for a finale, they’ll be performing the stunt we’re on set today to watch: them swinging down a zipline into a concrete wall with enough force to shatter every bone in their bodies.

First, they’re doing a dry run of the action sequence with a dummy – which is clearly a very serious health and safety test, and not at all an attempt to generate a spot of televisual jeopardy. “This is a drop zone area!” shouts a crew member, as staff mill around beneath a mannequin dangling nine metres in the air. “Please do not use that door – it is very dangerous!” For some reason, the figurine is naked except for a Santa hat, scarf and harness covering their lack of genitals (although, weirdly, they do get their own crashmat).

“Three, two, one!” yells Dr Zoe Laughlin, the show’s boiler suit-clad scientific expert. She presses a massive button and the dummy swings on a zipwire into a wall containing a replica of the McCallister family’s french windows.

“Broken limbs! Cracked ribs! Punctured lungs!” exclaims Laughlin. “Damaged internal organs! Maybe a little loss of teeth …”

“A little loss of teeth?” splutters Khan.

The decision is made: they’ll need to rethink the stunt.

In fact, given how hugely dangerous these stunts are, this is very much the show’s raison d’etre: toning them down so they’re survivable. At one point, an on-set medic loudly rubbishes the very idea that Acaster can take a can of paint to the face and not end up on a one-way trip to a crematorium. “Your head would be completely deformed!” he says. “There is no way on earth I’d even think about giving anybody resuscitation after that!”

Related: Home Alone at 30: how the unlikely Christmas comedy has endured

Throughout the show, the experiments end up being markedly pared back. When Acaster is on the receiving end of a can of paint, the plan is to take it to his baking-tin-clad chest rather than the face. A piece of steak will be used like a meaty oven glove to protect him from the red hot doorknob. Khan will don a rubber suit to stop him from being electrocuted and avoid being given third-degree burns to the skull by topping his head with a damp nappy. This is clearly the booby-trap short straw, given the look of absolute glee that flickers over Acaster’s face on hearing the plan.

“I desperately didn’t want to take a blowtorch to the head,” he laughs. “I was very relieved not to do it. I couldn’t wrap my head around how you would actually be protected. That’s when you realise you’re not as good a friend as you thought you were – because you’re very happy for your mate to do it instead of you.”

For the zipwire stunt, the plan is to wrap Khan and Acaster in shedloads of bubble wrap – after testing it out on the dummy once more. The on-site doc is proudly listing the minimal medical supplies he’s had to utilise thus far on the shoot (“Two plasters. Two paracetamol. Two Nurofen – not related to the experiments”), while the crew hoist aloft a mannequin loosely adorned with air-filled plastic sheeting. This time, it has been stuffed with a bunch of entrail-sized, blackberry jelly-filled balloons that will be examined after smackdown, to show what would happen to a person’s organs in a world where our skeletons were as thin as the plastic of a shop dummy.

“Have we fucked with the mannequin a bit so it’s gonna break?” shouts the director. “So the jelly falls out? Shall we cut a hole in it?” The suggestion is ignored, Laughlin presses her giant button, the dummy swings into the wall and … its head falls off. “I think we’d better take a closer look,” says Laughlin.

Fortunately, not every part of The Unofficial Science of Home Alone involves potentially flamboyant injury. At one point, Khan and Acaster order numerous pizzas so they can recreate the moment where Kevin terrifies a delivery boy by playing him audio of a gangster calling him a “filthy animal”. But instead of using the clip from the original – again, presumably for legal reasons – they play a series of recordings of Acaster impersonating a cockney wiseguy. And they stop short of setting off firecrackers.

“Yeah, I didn’t want to give someone the fright of their life,” says Acaster of delivery staff whose bosses were in on the joke – even if they weren’t – and largely ended up looking a bit bemused. “We’re the ones who end up looking stupid, not the people who delivered the pizzas.”

There are also a number of incredibly cute scenes where Home Alone superfan Alex Brooker interviews the movie’s cast and crew, including Wet Bandit Stern, who spills the secret behind his distinctive scream of pain: “I howl like a woman screaming for her life.” Each segment is introduced by Acaster, in a tone of resentment that, initially, feels put on for comic effect. Although the more you talk to him about his track record with stunts, you do start to wonder.

“I did a show called The Wrestling that happens in Edinburgh, where comedians fight professional wrestlers,” says Acaster. “I was meant to be hit with a metal tray, and all I had to do was hold my hands up to block it – so it looks like it hits me in the face but doesn’t. I did that twice – two years, two different shows – and both times I forgot to put my hands up and took a tray to the face.”

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So, for all the deliberate playing up to camera of the danger of the stunts, Khan and Acaster are actually scared? “Yeah, if you see fear on our faces, it’s genuine,” says Acaster. “No matter how protected you are, if you’re at the bottom of the stairs and someone swings a paint can off the top step, you do get nervous. I was very worried I was going to forget all the stuff they told me, and this paint can was going to decimate me.”

Fortunately, he needn’t be too worried. As Laughlin, Khan and Acaster assemble around the mannequin to assess the damage caused by a fall from the zipwire, they discover that half of the balloons-cum-internal organs have burst. The on-set medic stands in the background, giving his professional opinion to bystanders: “The spleen could rupture. Or the liver. The tendon that runs into it’ll slice it like a cheesewire.” It’s Laughlin who has the final word, though. The way to survive this trick? “There isn’t one,” she says, ruling out even attempting it. “Science can’t help you.”

The Unofficial Science of Home Alone is on Sky Max at 9pm on 19 December.