Leon's name itself is a reference to Leon: The Professional. This is further driven home by the moniker of his signature sidearm, Matilda (named after the film's young female protagonist). The VP-70 was likely chosen as his weapon of choice as another reference to Aliens, where the same pistol serves as the USCM's sidearm.
Leon's armored police uniform looks nothing like that of any other member of the RPD, but it does resemble the SWAT outfit Peter and Roger wear in the original Dawn of the Dead, except with integrated body armor.
Playing as Sherry is almost a direct copy of playing as little Grace in Alone in the Dark 2.
The G-creature chestburster scenes come from Alien, Claire's surrogate mother role towards Sherry mirrors Aliens with Ripley and Newt's relationship, the Tyrants are zombie Terminators, and Ada is derived from Nikita.
In the Underground Research Facility, Mr. X is taken out in a very similar fashion to the T-1000, but unfortunately, with different results.
Try yelling "Smile, you son of a bitch!" as you dispatch the giant croc in the recommended fashion. Just feels right somehow, doesn't it?
Resident Evil 1.5 had a few shoutouts that didn't make it into the finished product.
A hallway in the jailhouse, lined with holding cells containing disturbingly long-armed zombies reaching out through the bars, was clearly inspired by a scene from The Serpent and the Rainbow.
The remake restores it, but with fewer zombies (at least until the cell doors open...)
It also calls to mind the entrance hall of the pyramid in The Beastmaster, where the Death Guards reach through the slots in the walls.
The prototype also had an Aliens shout-out when Leon says "That's just fucking great" after being left behind by a fleeing police helicopter, quoting Pfc. Hudson after the evac dropship crashes.
Birkin's forms seem very reminiscent of the mutating creature in The Thing (1982). His final form is similar to the titular monster from The Blob (1988).
Birkin also bears a striking resemblance to Dora Franke from Kyōryū Sentai Zyuranger, an undead monster that progresses through several different forms. Its final form, Satan Franke was a particular influence, with its fleshy, red and brown color palette; grey, hideously elongated head and an additional humanoid face embedded in its chest.
On the street where the B Scenario starts you can see a DeLorean DMC-12 crashed near one of the buildings, a clear reference to the Back to the Future trilogy.
Another reference to Back to the Future (specifically the 3rd movie) is found in the STARS office, on the bulletin board above Rebecca's desk, where a heavily digitized BTS photo of Doc, Marty, and Clara is pinned.
In the hallway outside the room where you get the bronze gear, one of the boards covering up a window has REDRUM written on it. It is, however, very hard to make out in the original — luckily, the remake brought it back and made it easier to see.
In the first floor, west wing, there's a hallway with boarded-up windows; at one point in the game, zombie arms will reach through the gaps in these boards and try to grab your player, a sequence inspired by the climatic zombie attack in the original Night of the Living Dead. It also doubles as a Mythology Gag, since there was intended to be a sequence where the player has to navigate through a jail with the cells full of zombies reaching out through the bars in Resident Evil 1.5 before it was cancelled (with the especially long arms on these imprisoned zombies seeming reminiscent of a scene from The Serpent and the Rainbow).
Remake:
Leon's "Arklay Sheriff" and "Noir" costumes in the remake are presumably so named because calling them "Deputy Grimes" and "Det. Castellanos" might have caused some legal issues. The Walking Dead reference goes even further in the intro, which looked straight out of the TV series.
Elliot in the remake gets ripped in half by a hoard of zombies very similarly to Captain Rhodes in Day of the Dead.
The new name for Claire's Handgun in the remake, JMB Hp 3, is a reference to the designer of the gun and it's real life name (John Moses Browning and Hi-Power respectively).
Claire's gun isn't the only one with an obtuse and punny name, as Ada's pistol is called the Broom Hc. This seemingly odd name for a gun makes sense when you realize that it's Mauser HSc, made by the same company that made the Mauser C96, a gun also known as "the Broom Handle", thanks to its distinctive grip.
In the remake, Chris's desk has a couple of CDs that can also be found in Dead Rising.
In addition, a disaster notice in the game makes references to a freelance photographer by the name of "Frank East".
A Colombian Roastmasters standee can be found at the gas station at the start of the game.
In the remake, when Sherry is being chased by Irons she locks a door to keep him out only for Irons to ax the door down, a clear reference to The Shining.
Underneath the precinct map on the blackboard in the Operations room are the crossed-out names of several staff members who worked on the original game. A similar list can be found on the plaques at the foot of the Goddess statue in the main hall.
One of the Umbrella NEST scientists is named Cyril Archer.
Claire's motorbike in the remake has the license plate MD3 IN H3VN. When observed carefully it actually makes out the words "Made in Heaven", which is not only a Queen reference but a reference to the back of her jacket from the original game.
Speaking of her original jacket, the default one in the Remake has the same symbol as it stenciled on the back.
The name of Leon's handgun in the Remakenote Itself taken from Resident Evil 4 is "Matilda", a reference to The Professional, where the main characters are named Léon and Mathilda. It's also Stealth Pun, since Leon's partner, Ada, is a reference to Nikita, and Léon from The Professional was based off of the character Victor the Cleaner in Nikita, both of whom were played by Jean Reno, and both films were directed by Luc Besson.
Oh no, it doesn't just stop there, as the license plate of his Jeep at the start of the game also reads "M4T-ILD4".
Leon's starting handgun is also based on the H&K VP70M, which as its in-game description notes, was a commercial failure due to numerous factors, including a notoriously heavy trigger pull. Its primary claim to fame, and likely why it's in this game in the first place, is that it was the standard sidearm for the Marines in Aliens because it looked "futuristic."
Sherry Birkin throwing the jar of acid at Chief Irons to escape is very similar to what Fiona can do to Riccardo in the video game Haunting Ground, a lesser known Capcom survival horror game which shares certain elements with Resident Evil. The acid also only burns the left side of Irons' face, making him look a bit like Two-Face.
Leon's "Lightning Hawk" gun is a shout-out to another Capcom game. A synonym of Lightning is, after all, Thunder, and you get Thunder Hawk....or T. Hawk for short.
In the morgue one can find numerous blurred photos on the walls, and one of them happens to be the blurred visage of the deceased Laura Palmer from Twin Peaks.
A locker nameplate can be found in the police station with "JoJo" written on it, a reference to the manga series JoJo's Bizarre Adventure. This one is carried over from the original game.
Similarly, the store Arukas returns in the remake and can be seen at the start of the 1st Run. This is a reversed reference to Sakura Kasugano, a character from Capcom's Street Fighter series.
The achievement for using a flash grenade on a Licker is named "Keep Their Heads Ringin'", a reference to the song of the same name by Dr. Dre.
in the game makes references to a freelance photographer by the name of "Frank East".