Hallucinations (the bouncing Bonnie Booty that covers you screen) are somewhat tied to your sanity, I'm not sure how to get rid of them on the mobile version, hang out in the office to increase your sanity, hang out in the vents to decrease it. They can appear seeming regardless of you sanity, and lower it.
Objectives are in the "tasklist" at the top left of the screen on PC version, find the objects on the list at there semi-random spawn locations by searching the marked areas on this map.
In order to unlock the other animatronics you must progress to the night they appear by completing the objectives for the night and leaving without getting caught.
Night 1: Bonnie only; Enter the kitchen then the office.
Night 2: Bonnie & Chica; Find the Pizza and Cupcake, then enter the arcade.
Night 3: Bonnie, Chica, Fexa; Find the toy blaster and party hat, then enter
Night 4: Bonnie, Chica, Fexa, Fredina; Strip Fexa and Fredina, then enter the bathroom.
To see the game over scenes you have to get caught by them, there is no gallery.