There is a secret cameo... and it is not listed in the film's pre-released credits.
Shazam! is set squarely in the DC Extended Universe — which means the Justice League are very much a part of it.
So do any of the Big Red Cheese's comicbook stablemates make an appearance in the film?
Spoiler alert: Yes. Three of the Justice League are strongly referenced, and one even shows up in person.
Billy Batson's new best friend and adoptive brother Freddy — played by "It" actor Jack Dylan Grazer — is a huge superhero buff, and has tons of merchandise, most of it looking like Warner Bros. film swag.
He wears a Superman backpack to school, rocks an Aquaman T-shirt, and has a replica Batman baterang, just like the ones Ben Affleck uses.
He even has a real bullet, certified and authenticated, that was recovered after bouncing harmlessly off the Man of Steel's chest.
In another nod to their shared universe, during a climactic battle between Shazam (Zachary Levi) and super-villain Dr. Thaddeus Sivana (Mark Strong), an awestruck child catches sight of them while re-enacting a battle between Superman and Batman action figures.
But in one super sweet scene towards the end of the film, Shazam himself shows up at school to prove to the packed cafeteria he is indeed BFFs with Freddy — and he brings along a Super Friend.
Superman walks into the cafeteria, carrying a tray of lunch, and joins them at their table. Although we never see his face, it is the same suit Henry Cavill rocked in "Man of Steel", "Batman Vs Superman" and "Justice League".
But is it Henry Cavill himself? The jury is still out, as the secret cameo is not listed in the film's pre-released credits.
The writers also take a good-natured poke at another one of their own, buried right at the end of the credits in the film's second post-credit scene.
The scene actually appears to be a deleted one, and one which also already showed up in the Chinese trailer for the film.
As Shazam continues to try to figure out which super powers he has, he attempts to talk to a goldfish in a bowl.
"Don't beat yourself up buddy, you're going to find someone. Yeah, I'm sure because there's plenty of fish in the sea," he tells the fish to no response — an obvious swipe at one of Aquaman's much-derided super powers.
"What could we do with that that's cool?" he demands of Freddy who, pointing to his Aquaman-branded shirt sarcastically fires back: "Uh, maybe command an army of billions in the ocean?"
The genuinely hilarious Shazam hits theatres on Friday April 5.