- Floyd Lawton's civilian outfit in a flashback resembles the original, Silver Age Deadshot costume.
- Joker's costumes in the movie offer a ton of these:
- The Joker's purple dress shirt with a silver suit jacket is based on his Batman: The Dark Knight Returns costume. Set photos and video show a deleted scene where the Joker actually wears the full white suit from Dark Knight Returns.
- Joker is also seen in a standard black tuxedo, which appears to be based on a memorable illustration by Alex Ross, with Harley Quinn wearing her iconic harlequin costume (picture).
- Joker having a "Damaged" tattoo on his forehead is a reference to Joker having a bullet wound in his forehead in Batman: R.I.P..
- Tattoos aside, the Joker's shirtless look is straight out of Batman: R.I.P..
- Jared Leto has teased that the Joker's tourist look from The Killing Joke will appear
. It doesn't, but its possible appearance in a deleted scene remains to be seen. - A few scenes show him wearing a brown/orange waistcoat over a white dress shirt, which he wore in Brian Azzarello's Joker.
- The scene where Joker tortures Harley borrows imagery from his torture of Robin in Batman Beyond: Return of the Joker.
- Harley Quinn uses a baseball bat as a weapon, as she did in the Batman: Arkham series (as well as the New 52 series). Her iconic mallet also makes an appearance.
- Harley Quinn's speech from Joker's Favor is written on her baseball bat◊.
- Joker paraphrases one of his iconic lines from Tim Burton's Batman (1989).Joker: I can't wait to show you my toys.
- One scene has Harley acting as a stripper, as she did in Brian Azzarello's Joker.
- The Joker once again produces a grenade while waving bye-bye and leaving a room.
- There's a Freeze-Frame Bonus of Harley's red and black costume crumpled on the ground at one point. At another point, during the group's Lock-and-Load Montage, Harley finds the suit, playfully holds it over her body… then tosses it aside. Then, she pulls out the mini-bikini that her The New 52 counterpart wore. The red and black costume turns out to be more than just a Freeze-Frame Bonus, as Harley dons it earlier in a flashback montage that sees her dancing with a tuxedo-clad Joker, effectively bringing to life the aforementioned Alex Ross illustration.
- The team comes across a John F. Ostrander building during their mission, obviously named after the renowned writer of the Suicide Squad comics.
- El Diablo creating a moving flame sculpture of his wife inside an upturned glass can bring to mind the best known screen adaptations of Mr. Freeze.
- The death of Slipknot after Boomerang encourages him to run, saying the bombs are just a bluff. In the comics, Boomerang does much the same thing and Slipknot loses his arm to the explosive bracelet. In both cases, this was Boomerang just testing if they were serious about the bombs.
- Harley Quinn's origins alternate between her willingly joining the Joker and being tortured to the point of Stockholm Syndrome. This, combined with her moments of introspection as she tries to reminisce are traits shared by the Joker in The Killing Joke.
- The film shares a few striking similarities with Batman: Assault on Arkham:
- Both films include a montage that introduces every Squad member with a flashy intro screen.
- A Sacrificial Lamb character is introduced simply to show the explosive collars in action. In Assault on Arkham, it's KGBeast, and in this film, it's Slipknot.
- In both, the bad guys are accompanied by an assassin who considers himself/herself morally superior to the criminals. In Assault, it's Black Spider, and in this film, it's Katana.
- They both have a climactic scene in which the Joker helps Harley escape via helicopter, and both scenes end with the Joker seemingly perishing when the helicopter crashes and explodes.
- Out of the Squad, Deadshot is given the most amount of focus, and essentially becomes the film's most major protagonist. Also, both Assault on Arkham and Suicide Squad close with Deadshot getting to spend quality time with his daughter.
- In a bit of inversion, in Assault, Captain Boomerang is happy to go on another mission if it means time off his prison sentence. In Suicide Squad, Boomer takes objection to a bit of measly time taken off a triple life sentence and tries to force Amanda to release him outright. It works about as well as you would expect.
- Both films end with Bruce Wayne/Batman confronting Amanda Waller.
- In a few scenes, Jared Leto seems to be imitating the voice Mark Hamill used for the Joker in Batman: The Animated Series. In others, he uses a low growl similar to the voice Heath Ledger used in The Dark Knight.
- Somewhere between here and Composite Character: El Diablo's powers apparently being magical in nature and stemming from a case of Demonic Possession refers to both the 1970 El Diablo, Lazarus Lane, and the Pre-Crisis El Diablo, Rafael Sandoval. For added reference, El Diablo's demon is an Aztec-themed spirit, just like Sandoval's.
- When Deadshot is assigned to kill another gangster, he uses equipment that he positioned at a precise angle for the bullet to bounce off and hit the target. The guy who hired Deadshot? Angelo. A subtle nod to Angelo Bend, aka Angle Man.
- In Captain Boomerang's flashback spot, we learn that he wound up in prison after he was apprehended by the Flash during a bank robbery. In the comics, Captain Boomerang was a prominent member of "The Rogues", a group of recurring enemies of the Flash known for their colorful costumes and gimmicks, their relatively harmless crimes, and for being on surprisingly friendly terms with the Flash.
- Deadshot's intro screen◊ is an exact recreation of an iconic comic book cover featuring the character◊ (Secret Six Vol. 3 #15), right down to the raining bullets.
- One person asks what if (the for now? deceased) Superman attacks the White House and gets the President. Which is what the Justice Lord Superman did (except he killed President Lex Luthor). He also did something similar to the United Nations in Kingdom Come.
- Sunny Jim from Lobo (Webseries): His face appears at the front of a store.
- At the end of the film, we see some of the cast getting their rewards for helping Waller. Except Boomerang. Boomerang's just screaming in his cell like a chump. In the comics, Waller hates Boomerang so much that even when he's not on the Squad, she's gone out of her way to kidnap him and pressgang him into missions.
- During The Stinger, Waller implies that she knows Bruce Wayne is the Gotham Bat in a threatening tone. In other words, she believes one of the richest, most powerful people in the world is secretly a vigilante who spends his nights beating criminals to a pulp with his bare hands, and her plan is to blackmail this person. Bruce's response is a fair warning that that's a bad idea.
- During the helicopter escape, Joker tells Harley that he has some grape soda waiting for her. Harley could be seen drinking grape soda in one of her most iconic comic books, Paul Dini's "Mad Love", while she had Batman in a death trap.
- The speech about Superman tearing the roof of the White House and kidnapping the president becomes funnier when you realize a similar situation has happened before in Superman II and Kingdom Come.
