The links attaching Shazam's cape to his shoulders have tigers on them, a reference to long-time Shazam supporting character Tawky Tawny, an anthropomorphic tiger. The toy shop in which a scene takes place has stuffed tigers, meanwhile — in the 1990s Power of Shazam! series, Tawky was originally a stuffed tiger doll possessed by a friendly spirit.
In a flashback, Billy asks his mother to win him a stuffed tiger at a carnival dart booth.
There's a tiger on Billy's backpack.
Doubling as a Shout-Out to the Rocky films, Billy demonstrates his lighting powers while "Eye of the Tiger" plays.
There is a silver bunny towel rack and bunny picture in the Vasquez kitchen, this is a homage to Hoppy the Marvel Bunny.
Fawcett Central School is named after Captain Marvel's original publisher Fawcett Comics, similarly to Power of Shazam!, which had Fawcett City as his home base. The use of Philadelphia as the basis/counterpart likely references Billy living there in New 52 and DC Rebirth continuity.
Billy's civilian outfit, with the jacket and the beanie, harkens to his appearance in Jeff Smith's Shazam! The Monster Society of Evil.
The intense and dramatic way the Wizard lists the powers of Shazam is also straight out of that series.
Doctor Sivana wears a button-up khaki tunic underneath his coat, a nod to the character's ever-present lab wear (especially his earliest incarnation◊, which had a green pharmacist's coat, not a white one).
Fans noticed a plethora of smiley faces on the foster care counselor's desk and asked David F. Sandberg if it was a Watchmen easter egg. Sandberg not only confirmed but also showed the desk from a different angle, showing an all too familiar blood-stained smiley face button hidden behind the counselor's name tag.
The skate ramp where Shazam tests his flight has "Arion" graffitied on it. Arion is the name of an immortal Atlantean sorcerer in the comics who's been both a hero and a villain. The graffiti even has the star inside the "o" from the logo◊ of the 1980s comic book Arion: Lord of Atlantis.
In a Freeze-Frame Bonus, one of the videos on Freddy's Youtube channel gives him the name "Captain Thunder", which was originally supposed to be the characters name before Captain Marvel was decided on (and still is in some alternate continuities)
The mainland Chinese trailer has a shot of a little boy humming John Williams' iconic Superman theme while playing with his Superman and Batman action figures. In the actual film, the John Williams theme is used during Superman's cameo at the end.
The Hong Kong trailer has a Tag Line that roughly means "Marvellous Saviour", alluding to Shazam's previous name.
During the wizard Shazam's Exposition Dump of his origins, he alludes to a previous champion, chosen a thousand years ago, who turned bad and released the Seven Deadly Sins upon humanity.
When Billy and his siblings are trying to leave the Rock of Eternity by opening a bunch of doors, one of the doors leads to a room of crocodile people playing poker. This is a reference to the Crocodile-Men, variously alien/magical thugs usually seen in the employ of the Monster Society of Evil as cheap muscle.
Billy and his siblings are adapted from the New 52/DC Rebirth Shazam Family, itself a composite of the Captain Marvel Family, Flashpoint Captain Thunder, and a bit of the original Captain Thunder concept:
Like with the Marvel Family, there is Billy, Mary and Freddy, but like with Flashpoint there is also Eugene, Pedro, and Darla.
Like with the Marvel Family they all can transform to their super-powered older selves, but like the original Captain Thunder concept with the exception of Shazam the others specialize in one power.
Seen at the Rock of Eternity is the Magic Mirror from DC's New 52 era, which contained Billy's supernatural ally, Francesca.
Also at the Rock is the magic wand called the Ibistick of Ibis, the key magical device used by the Egyptian magician Ibis the Invincible.
Also appearing is the Burning Violin from 1946's Captain Marvel Adventures #64. In that issue Oggar, another fallen pupil of the wizard, enchanted the violin of his henchman Nero to spew fire, and it almost burns down New York City.
The abandoned factory where Freddy records Billy testing out his powers is an old Ace Chemicals facility.
Billy's first words spoken on-screen are "Holy moley, the boys in blue!" as part of the very insincere gee-shucks act he's playing for the cops. He later uses the phrase twice, and genuinely, to express quiet terror.
Billy's parents are C.C. and Marilyn Batson, who first appeared in the "Power of Shazam" comic.
Furthermore, C.C. was named after Captain Marvel co-creator C.C. Beck.
Additionally, in the "Power of Shazam" comic, CC and Marilyn Batson were former champions of the Wizard thanks to tampering with the space-time continuum.
The Seven Realms mentioned in the first stinger make their first appearance in Geoff Johns' 2018 Shazam! ongoing, where they can be visited from the Rock of Eternity.
When Freddy gains his superhero form it has an Elvis-style pompadour haircut. Freddy Freeman, aka Captain Marvel Jr, was music icon Elvis Presley's favourite comic book hero, which in turn led to Freddy becoming an Elvis fan in the comics.
Billy finally masters the ability of flight after being dropped from a great height by Dr. Sivana. This manifests as him nearly hitting the ground, only to stop just an inch or two above it, hovering. This is reminiscent of a flashback scene of a young Clark Kent in Superman Returns.
One of the superhero names used early on, Red Cyclone, is not too far from Red Tornado.
The security guard's name's last name is Moran. Mike Moran was the real name of Marvelman/Miracleman, a British Captain Ersatz of Captain Marvel. note According to Sandberg, this gag wasn't intentional and Moran is just the namesake of a member of the prop department.
The hobo in the bus scene has an uncanny resemblance to Alan Moore, the writer of Miracleman.
Billy-as-Shazam puts on some normal clothes over his costume to pose as a legal guardian for himself and Freddy in order to get them out of school, not unlike Billy used to do in The Power of Shazam! in order to convince school officials that he was still under the care of his uncle (who had thrown him out and kept his parents' money).
Sivana Industries first appeared in the "Power of Shazam" comic, but was run by Thad Sivana himself rather than his father.
Billy is briefly shown playing Mortal Kombat X as Raiden; In Injustice, made by the same people as Mortal Kombat, Shazam's moveset is partially based on Raiden's.
Costume designer Jerad S Marantz has cited the Shazam costume design to be influenced by Shazam's appearance in Justice League: War, as seen here.
Freddy Freeman's Golden Age suit
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