Trivia: At the theater Clayface is watching "The Terror" a movie starring Jack Nicholson, who played the Joker in 1989's Batman.
Suggested correction: More likely, this is a reference to Clayface's origin in the comics, where he was an actor who starred in a film called "The Terror," then dressed as its killer and killed the cast and crew of a remake set to be made without his involvement (his shapeshifting powers coming later into his character's life). This is evidenced by how the film on the projection screen appears to be a black and white film from the 30s-40s, matching Clayface's first appearance in comics.
Trivia: Just before Protocol 10 starts, you end up in a giant fight with Joker and a good number of his goons. If you activate Detective Vision during this fight, you'll see that Joker doesn't have a skeleton. This is also true when he's holding Talia hostage in front of the move theater. This offers a hint to how the plot plays out.
Trivia: When doing the side-mission "Enigma Conundrum", after going to where the first Riddler room is located, look up and you will see a sign for a place called "The Black Canary." The Black Canary is another DC Superhero and member of The Justice League.
Trivia: In addition to Black Mask, there are two other cameos in the game's intro sequence. When you're making your way through the prison line, one of the prisoners says to Bruce, "You're on my list," and pretends to shoot him with his finger. This is Deadshot, who would later appear in one of the game's side missions. A little bit later, after you go through the armored door, look up at the roof of the building towards the right. You can see Azrael, who disappears in a puff of smoke. Again, he later appears in one of the game's side missions.
