1
Attachment In Chapter 14 (The Consequences DLC), before entering the final boss fight, if the player shoots Ruvik's brain, it will trigger a fake ending with a photo of Sebastian, Joseph & Kidman congratulating the player (similar to Resident Evil (2002)'s easter egg photo of Chris & Jill congratulating the player for completing the Invisible Enemy mode. Both games are directed by Shinji Mikami.), earning a trophy/achievement called "Stick to the Script". After the credits end, it will cut back to the game where a startled Kidman will shout an expletive.
1
Attachment In Chapter 13, there are torn posters of graphics taken straight from 'Fallout 3 that read "Enjoy Vault Living!" and "I Love Sugar Bombs", as well as "The Hound Pits" and "The Golden Cat" posters (In Chapter 14, there's a larger version of the latter poster) taken straight from 'Dishonored'. Both games and The Evil Within were published by Bethesda Softworks.
1
In Chapter 4, you can find a wall of pictures of people with their faces blurred out and distorted, which is likely a reference to the film 'The Ring'.
1
Attachment In Chapter 2 (The Assignment DLC), when fighting Joseph, a projector can be found that plays 3 different films:

•A series of Rorschach tests played back rapidly
•A picture of Joseph with a sword
•A picture of Juli Kidman wearing a bikini that appears for a split-second
1
Attachment In Chapter 3 (The Consequences DLC), in the KPD station, if the player uses the flashlight on a specific empty desk, it will reveal a hidden computer on the desk and identification revealing the desk used to be occupied by Spoiler:Juli Kidman.
1
In Chapter 3, in New Game+ mode, when obtaining the chainsaw and after the Sadist is killed, a secret minigame can be found in a small room at the highest level of the barn. After climbing up to the room and shooting a small window on the wall just in front of the top of the ladder, a crow can be found which when shot will trigger the mini-game with a sweeping cutscene of the abandoned village. The locations of five different crows scattered across the village can be seen, which need to be killed in 2 minutes to earn 100,000 Green Gel.
1
Attachment In Chapter 9, in the library, there are books with the snail logo of Tango Gameworks, the developer team that created the game.
1
In Chapter 1 (The Assignment DLC), there's a broken double door that keeps opening and shutting. If the player comes closer and aims the flashlight at the gap, Laura Victoriano's ghost will appear, then disappear after she came too close.
1
At the start of Chapter 14, there's a vending machine witht the name 'Brain', that can be found at the bottom of the escalator. If the player interact with it, zombie babies will come out of the vending machine to attack the player.
1
In Chapter 3 (The Consequences DLC), there's a soda vending machine with a brand named "BRAIN". By interacting with it 15 times, a painting on the corner of the wall will fall to reveal a peephole. If you interact with it, you'll see a hidden room with a Shade dancing for three Haunted wielding glowsticks. The Shade will eventually notice your presence.
1
The music that plays in the save rooms is a rendition of Claude Debussy's "Clair de Lune".
sell
1
In chapter 6, Spoiler:saving Joseph's life from hanging on the bridge will award the trophy / achievement "Everybody Gets One".

This is most likely a reference to Family Guy, in "Let's Go to the Hop" and "Believe It or Not, Joe's Walking on Air" when Spider-Man says it to Peter Griffin and Cleveland Brown after saving them from a fall.
1
After the player gets out the crash site, they'll find Connelly who is eating a dead body. This is a reference to the original Resident Evil, specifically the player's first encounter with a zombie who is eating Kenneth. Shinji Mikami was the director of both titles.
1
The game's working title was "Zwei", the German word for "two". This was in reference to the game's original premise of two vampire hunters attached to each other by a chain.