Bullet Train director, David Leitch, told Forbes he sees his latest film starring Brad Pitt as a universe. There's no clear sign that a sequel is in the pipeline but from Leitch's comment, it seems he'd be only too pleased to take the adaptation of Kôtarô Isaka's bestselling book to the next level. The novel follows several highly motivated hitmen aboard a Tōhoku Shinkansen Hayate Train, interconnected somehow by way of their separate missions. Taking Isaka's satirical dark comedy undertone, Zak Olkewicz ramps up a similar atmosphere aboard a Bullet Train where a briefcase of money becomes the crux.

You could describe Bullet Train as a mix of Source Code and Kill Bill: Vol. 1, creating a similar situational dynamic as the Jake Gyllenhaal train thriller with the stylistic lashings of the Uma Thurman actioner. Acts of terror, explosives, suspicious circumstances and a train - it's easy to draw parallels with the Duncan Jones sci-fi thriller, Source Code. Diverging at the point of the Quantum Leap type hero, Bullet Train branches out into the same eclectic and violent showdown that is Quentin Tarantino's Kill Bill: Vol. 1.

Leitch must have used a few Quentin Tarantino and Guy Ritchie movies as a reference or jumping off point. Or being a fresh adaptation, Bullet Train's bankability may have rested on the idea of pumping up one of these stylish action flicks now that the two most prolific names have slowed down on delivering their own trademark movies. Perhaps the popularity of the stellar Murder on the Orient Express may have given more impetus to the decision to base a film primarily on a series of train carriages - although films like Snowpiercer, The Taking of Pelham 123 and Unstoppable have also demonstrated some groundswell over the last decade.

Although as much fun as these kinds of films can be, none of the aforementioned train-based thrillers has derived a sequel. So one has to imagine the biggest obstacle is finding another reason to do it all over again on a train. As much as David Leitch wants to expand this universe, it hardly seems feasible with "Bullet Train" in the title. It's a great title and makes complete sense based on sharing its name with the book, however, it's too limiting. This rinse-and-repeat for a sequel just seems like too much locomotion even for the most ardent of action fans.

It helps that they'd need to replace most of the cast and have a few loose story strands that could be explored, but it's too locked into Japan and the train setting. Perhaps the only thing they could do is pick up on a flashback to create a prequel to give a broader explanation of how they hitmen all arrived on the train. Having the likes of Sandra Bullock, Ryan Reynolds and Channing Tatum chiming in with varying degrees of success with cameos could also open a few avenues. Strangely enough, all three are connected by the fun movie Lost City along with Brad Pitt, which makes you wonder about the possibility of some high profile favours being cashed in.

Although, based on recent naming conventions with the Knives Out sequel, Glass Onion: A Knives Out Mystery, it seems anything goes. Huddling enough big name actors onto a train worked for the Kenneth Branagh-led Murder on the Orient Express, which turned into the sequel Death on the Nile, so these days it seems that you can tip the balance if your ensemble's collective star power turns into a "where there's a will, there's a way" opportunity. Just make sure none of them are ripe for a tabloid-grabbing scandal.

Thankfully Leitch's Bullet Train doesn't have the painted backdrop feel that the Poirot refresh Murder on the Orient Express had, doing its homework to create a more tangible environment within a more realistic world. Throwing in loads of pop culture references to an animated show, Thomas the Tank Engine types and a Lord of War "life of a bullet" style ad for Fiji water, keeps things light, fluffy and flashy for audiences. This playful spirit helps downplay the clang of "advertisement" and softens the edges of reality, which are already stretched enough to make you think Isaka wrote a graphic novel.

So, while there aren't any sequels to similar films that lay enough track to suggest a "Bullet Train 2" is even possible, it's the kind of nutty action comedy entertainment that seems immune to any speculation. The high ratings for Bullet Train on IMDb suggest the dark comedy and violent action struck a chord, possibly stoking up the embers left by Tarantino and Ritchie. So this critic-proof dimension, the escapist folly, box office profitability and fun-spirited nature of the take-no-prisoners movie makes it seem like a special case.

Having been at the helm of John Wick, Deadpool 2 and Atomic Blonde, one has to think David Leitch does know what he's doing? Maybe he doesn't but is operating with such resonant intuition, it hardly matters. While his foray into Hobbs & Shaw seems like a misstep, mixed reviews from movie critics and film pundits couldn't stop Bullet Train from rocketing to almost $240 million, so Leitch does seem to have his finger on the pulse on what mainstream audiences really want when it comes to action, stars, style and way over-the-top storytelling. It seems that finesse, consistency and nuance just aren't as important as giving viewers a few classic scenarios and chuckles to rehash after all's said and done. Who knows, maybe John Wick will find himself buying a ticket for a train trip sometime soon?