Brewing foamy fake beer might be more difficult than making the real deal.
In "The World's End," five men embark on an epic pub crawl -- 12 stops -- and the actors obviously cannot drink real or even near beer and remain upright, wide awake and able to recite their lines.
It took some effort to hit upon the right frothy formula, actor Nick Frost said in a recent phone interview.
"Even if you drink 0.001 alcohol-free lager, we found there is an odd kind of placebo effect. And then we thought maybe apple juice or some kind of carbonated apple juice, and that didn't work because the high sugar levels made us all really jittery, like young children eating a lot of sugar.
"Eventually we settled upon a lightly carbonated water with a slight burnt caramel solution to give it that lager color, and then we had a guy whose job -- literally -- it was solely to make a foam out of cream soda and tiny bits of egg white to give it some head. He would come on, spoon the head on and we'd crack on."
For scenes near the end of the movie, the production actually used "beautiful fizzy lager."
"The World's End" reteams director Edgar Wright with actors Simon Pegg and Mr. Frost from "Shaun of the Dead" and "Hot Fuzz."
The two, along with Paddy Considine, Martin Freeman and Eddie Marsan, portray onetime high school friends who improbably reunite for a pub crawl expected to end at a bar called The World's End. Turns out it may be the world's end, too.
The apocalypse is much on the minds of moviegoers this summer, but Mr. Frost said the idea for this project originated seven years ago.
"Me and Edgar and Simon tried to do a crawl about eight years ago because the film is based on a crawl [Edgar] did when he was 19 and he got through about six pubs. Then, the three of us went back about eight or nine years to try it, and, sadly, Edgar only got through three pubs.
"He is the lightest, the worst drinker in the world, and it's always a drag going out drinking with Edgar because it essentially is over at 9 o'clock and then you're left wondering, what am I gonna do for the rest of the night?"
Mr. Frost's last real pub crawl doubled as his bachelor party.
"I think I remember pub seven, and then my friend Andrew turned up with a giant glass -- Eiffel Tower -- filled with absinthe, and that was that. That's all I remember. I woke up and I was married."
Now 41 years old, Mr. Frost has known Mr. Pegg for two decades. He was 21 when he worked in a Mexican restaurant with Mr. Pegg's then-girlfriend, who kept suggesting he meet her boyfriend, a stand-up comedian.
The men eventually met at a party, and it was laughs at first sight. "We instantly hit it off. About three weeks down the line, we realized that we'd essentially spent every day together," he recalled.
"That was it. We've been inseparable ever since."
As for what happened to that erstwhile girlfriend, he asks with a laugh, "Who cares? I got him in the divorce, so that's all I care about."
In "The World's End," Mr. Pegg plays Gary King, the irrepressible and irresponsible leader of the mates who have gone their separate ways in the past two decades. As Andy, Mr. Frost once was Gary's closest friend, but a long-ago incident drove a wedge between them.
It was a given that the parts in "The World's End" would be parceled out that way. "We tried to change it slightly in 'Paul' in terms of the roles," he said of the road-trip comedy about visiting Englishmen on their dream tour of UFO hot spots when they encounter an actual alien.
"I think it's really important for Simon and I to do different things within the thing we do so people don't get bored of it. I think it's very easy to slip into that Simon is the straight-edged, hard-ass overachiever and I'm his kind of wisecracking sidekick. That would be perfectly acceptable, but that would get boring quickly.
"We're both actors, and it's always a challenge to play something different, and I think in this one, Simon was the center and the lunacy and I was, essentially, the moral audience, having to look at him and ask the questions that perhaps the audience wants to ask."
The pair would love to play enemies, but that could mean one would be in the first half of the movie, the other in the second and they would meet only at the end.
Although each could stand on its own, "The World's End" is the third in what's called the "Three Flavours: Cornetto" trilogy. It, "Hot Fuzz" and "Shaun of the Dead" each feature a cameo appearance by Cornetto ice cream and a gag about falling through or smashing fences.
"The films are about growing up, as we've grown up, as men, so our characters have grown up. It's inevitable. I think it's always weird when you watch man comedies and you see 45-year-old men playing 26-year-olds, but you got two kids, you're quite old, why are you playing this character?
"I think it's important to us that our characters age as we do. The connective tissue is friendship, and the different kinds of male friendship and the evolution of male friendship and how they must evolve -- this is all friendships and marriages -- or they sadly wither.
"Also, the individual against the collective, that's in all three films as well."
Sometimes that means physically battling the collective of enemies in a bar or its restroom, which was destroyed, rebuilt and destroyed again for one key sequence. "I think Edgar was keen that the actors did them all," with big, long takes of the fights.
The director met supervising stunt coordinator Brad Allan, who worked and trained with Jackie Chan on the set of "Scott Pilgrim vs. the World," and hired him to help choreograph the fights.
"We spent four weeks getting our fitness levels up and learning these fights, which were amazing. They were such fun to do. I mean, very intense, just 12-hour days, every day, of fighting. The biggest fight took 10 days to shoot.
"I was very lucky that a week before we started the rehearsals for 'World's End,' I had just wrapped a film where I learned and trained to become a dancer. I trained seven hours a day, every day, for seven months to become a Cuban salsa dancer. So I think I was very lucky that I did it that way around."
The romcom "Cuban Fury" also stars Rashida Jones, Chris O'Dowd, Ian McShane and Olivia Colman and features Mr. Frost as a man whose shabby, overweight exterior hides the heart of a salsa king.
Is he still dancing? "Absolutely. The first thing I did when I sprang out of bed was I did a basic salsa step."moviesvideo