Criminal Case has a number of references to a number of other games, shows, and franchises. Examples are listed below, and the list is continuing to grow.
At the end of Zeus's side-quest in Case 6, as a reward he gives you a pair of glasses to help you style up your looks. The glasses in question have a red-colored frame with tiny yellow lightning bolts on the sides, and they're called "Flash Goggles."
A possibly unintentional one in Case 7: on completing one of that case's side-quests, you receive a necklace as a thank-you gift, which looks a lot like Tsunade's necklace. The necklace itself can be worn as an accessory on your character avatar.
In Case 8, Jones refers to suspect Lydia Holly as "Miss Marple," due to her extreme fascination with murder mysteries.
Chad Whickman, the victim in Case 9, dies after being set on fire. Both his surname and the manner of his death bring The Wicker Man to mind.
In Case 10's Backstreet scene, one of the hidden items is a shadowy bat overlooking the crime scene, which looks suspiciously like the silhouette of the Dark Knight. Makes one wonder how come Grimsborough's crime rate hasn't gone down if he's around...
Jason's mask is one of the hidden objects in the Grimsborough Cemetery in Case 26, while a Michael Jackson-lookalike can be seen dancing among the tombs in his famous Thriller outfit. As well, the Necronomicon plays a role in Case 26 overall.
Case 34's Bunk Beds scene has a poster on the wall, depicting an Asian man in a Bruce Lee pose (though the man in the poster is wearing a jacket and has a beard).
In the Exam Table scene in the same case, one of the hidden items is Ghostface's mask.
In the Hacker's room scene in Case 35, a replica of V's mask can be seen on one of the computer screens. There's also a wall of green digital text, albeit not on any of the computers.
In Case 37, the victim is dressed as a Star Trek ensign, while one of the suspects is cosplaying as a character from Avatar. Also, in the Festival Stands scene, the Ripper Jade statue in the middle of the room has a familiar red-and-black spider-web pattern on its stomach, and Batman's mask is one of the hidden items (albeit with mouse-ears instead of the traditional pointy ears).
The Diner scene has among its hidden items a black T-shirt with the yellow Bat-logo, only with mouse-ears, and also Ghostface's mask shows up again. Okay, are we sure Grimsborough isn't an alternate-universe version of a Gotham City where Batman changes his mask-fashion daily and is hunting Ghostface?
The Diner Tables scene includes Thor's hammer among the hidden items.
In Case 45's Sun Chair scene, one of the items on display is a book titled "Fifty Shades of Blood," an obvious play on a certain other notorious book.