The virus responsible for the deaths and mutations of the locals is Type 2 Plagas while 3 were killed by Uroboros. Las Plagas was in Resident Evil 4 and the T-Virus and G-Virus with the Umbrella Resident Evils.
On February 10, 2010, Capcom released a "Lost In Nightmare" scenario for download. This scenario covers the events of the flashback Chris told to Sheva when they were boating on a fan-boat in the marshlands. And on March 4th, 2010, another scenario "Desperate Escape" will be released and that is based on Jill Valentine and Josh Stone making their escape between when Jill is restored to her normal self and when after the final battle.
The beginning of the mansion of the "Lost In Nightmare" scenario bears a striking resemblance to the mansion of Resident Evil Remake. Some resemblances include the main hallway's staircase, the rear staircase, the dining room, the stairway hallway that had a birdcage in the Remake game, the piano song "Moonlight Sonata" to be able to take an emblem, and to use that emblem to open a door, and a monster crashing through windows.
In "Lost In Nighmare" scenario, if you attempt to leave the mansion through the front door, you will be able to play the game using the camera angle style of the earlier Resident Evil games when the camera didn't move, but was still angle to still angle.
The "Lost in Nightmare" scenario has the fewest enemies in the game, and the fewest type of enemies. There's only two types of enemies, one of which includes the classic zombies that play dead on the floor.
By installing the "Lost In Nightmare" scenario, the file also comes with a new version of the mini-game Mercenaries, then called "Mercenary Reunion" where both Barry Burton and Rebecca Chambers, last seen in Resident Evil 1 make a reappearance.
Like the other playable characters in the game, Albert Wesker can also perform physical attacks on stunned enemies. One of these attacks is called "Tiger Uppercut" - a reference to a special move from the Street Fighter series, a game also developed and published by Capcom.
During the game a poster advertising an album by Paula Hopkins, entitled "Mother", can be seen on various walls in chapter 1-2. This exact same poster can be seen in a previous Capcom game; Dead Rising. The poster appears in the music shops around the mall and it's also the very CD that Frank can use a stack of as a weapon.
The large monster in "Lost In Nightmare" scenario that has reappears bears a resemblance to the mutated version of Steve Burnside from Resident Evil CODE: Veronica and fights similarly to an Executioner Majini hence its axe swing.
With the file extensions of "Lost In Nightmare" and "Desperate Escape" scenarios added to the Resident Evil 5 game, you have to collect the added trophies from the scenarios, and even in the "Versus Mode."
This is the first Resident Evil main series where if the player character switches equipped weapons, they'll physically swap weapons instead of going into a menu to change a weapon and exit the menu with a newly equipped weapon. Plus, it's the first of the main series where if the player opens the inventory menu, the game's action and time will not pause. Instead, it will run in real time, meaning that enemies will approach the players anytime to attack.