Lorne Michaels should send a check to Sony.

Because the studio’s sent him a love letter. In their new movie “Saturday Night,” a madcap comedy about the 90-minute dash leading up to the 1975 debut episode of “SNL,” the show’s famously enigmatic creator is lionized. 

Michaels, the most important behind-the-scenes comedic force of the past 50 years, is placed on an innovator pedestal alongside the likes of Steve Jobs and Mark Zuckerberg, only without their personal downsides.

He’s portrayed as an optimistic young underdog with an improbably bold vision: a completely live, weekly sketch series starring inexperienced, unpolished nobodies in a desert island of time slots.

His “This is Sparta!” speech comes during the climax, when Lorne (Gabriel LaBelle) is grilled by NBC exec David Tebet (Willem Dafoe) about what “Saturday Night Live” exactly is.

Michaels, finding his confidence in real time, tells doubting David it’s discovering a hot new comic at the back of a bar downtown, or being swept up by the music at a tucked-away jazz club.

“It’s everything you think is going to happen when you move to the city,” says a then-30-year-old Michaels. “That’s ‘Saturday Night.’” 

And that’s the stuff of goose bumps.

The David-and-Goliath confrontation is the best and most grounded scene in Jason Reitman’s never-less-than-likable film, which had its international premiere Tuesday at the Toronto International Film Festival. 

The plot barrels forward like the brakes are broken. And, being a Tour de Frantic, it can be hard to keep up. The gist is that this massive TV hit that spawned countless stars was nearly a disaster that didn’t make it to air. Execs were ready to roll a “Tonight Show” rerun instead. 

Knowing this is his only chance, Michaels races around 30 Rock and Studio 8H attempting to get his scrappy creation up and running.  

He must control his boisterous young stars, who treat the office as a kegger — or worse. John Belushi (Matt Wood, a find) refuses to sign his contract and heads to a bar. George Carlin (Matthew Rhys), the first host, gets lockjaw from snorting too much cocaine. 

The set’s not finished and the dress rehearsal ran three hours. An NBC page (Finn Wolfhard) stands outside on 48th Street begging passersby to be audience members.

On the periphery of the art, there are corporate concerns. The affiliates are in town to decide if they even want to air whatever this is. And whiny network stars Milton Berle (J.K. Simmons) and Johnny Carson are threatened by the annexation of their late-night turf. 

For a movie that’s barely longer than an episode of “SNL,” that’s a lot of ground to cover. And those “Noises Off”-style backstage snafus are just a small sampling of all the action. But Reitman ably crams it in, even if the onslaught occasionally gives us whiplash. 

Always in motion, “Saturday Night” can be a bit like if Joan Cusack’s sprint at the start of “Broadcast News” lasted for an hour and 45 minutes.

Since the characters barely get a chance to catch their breath, let alone say their piece, we don’t learn much about them beyond familiar traits. However, Reitman’s aim isn’t to seriously illuminate that fateful night so much as to energetically add to showbiz mythology. 

The director said onstage at the premiere that, during interviews, the real talents’ accounts of that first show all contradicted each other. We can tell, but the absurdity is part of the fun.

On Oct. 11, 1975, Gilda Radner, Chevy Chase and Dan Aykroyd were not yet household names. They barely mattered in their own studio. But over the course of that year, they’d explode. 

So it’s fitting that, in casting actors to play them, Reitman chose some of Hollywood’s most talented rising stars who America will soon know very well.

LaBelle, a revelation as a young Steven Spielberg in “The Fabelmans,” wows once again as Michaels, another dreamer. 

I never guessed that Cory Michael Smith, who I’ve watched for years onstage and in Todd Haynes’ films, would make such an uncanny and hilarious Chase with a gift for punch lines.

Cooper Hoffman, whose star-is-born moment came in “Licorice Pizza,” brings that same charming gumption to producer Dick Ebersol. And Ella Hunt exudes Radner’s easy effervescence. 

The cast is sadly too gigantic to list off. Some are skilled impressionists, while others manage to get to the meat of their person. Like the aftermath of a sketch being cut from an “SNL” episode, there are times when you wish you could see a lot more of certain performers.

In any case — and who would’ve thought I’d be saying this about a man who barely speaks — the real magic here is LaBelle’s Michaels. Live from New York, it’s Lorne!