Cursed Artifact #3/6: After you defeat the bellhop ghosts in the lobby (where you find Cursed Artifact #2/6), you’ll take a shortcut through the kitchen with Peter to get to the Bar Mitzvah. Blast your way past the Dead Fish Fliers. Afterward, Peter will explain how to move the metal container out of the way. Do so, and make a right down the hall, and another right into a room. Follow the path to the back of the area, where you’ll find a mini Stay Puff marshmallow man on a table. Scan it to get Cursed Artifact #3/6.
Ghost Scan #2/6: Make sure you scan one of the Dead Fish Fliers when you fight them in the kitchen. They don’t appear elsewhere in the level.