(Walkthrough for all Easter eggs!)
Hammer time: Click on the right eye on the main menu.
BTS/ Drawings and stuff: Click on the Square on the bottom corner on hair type menu.
Electroshocking: Click under from the piranha tank on the Torture menu.
Final Easter egg: Shooting Range! On the Acid scene. Click on the doll on the right who has the gun.
And It gives you hints on all of the Secret Easter eggs!
And once you found them all... Congratulations! You found all 4 Easter eggs!