Schrodinger's Capsule is similar to the regular Capsule. Except from having a yellow button Switch on top of it like any other Capsule however, this one is blue with different details, a transparent window on the front, orange prongs as feet, and what seems like a flat red lid covering the top.
Schrodinger's Capsule appear near the end of Angel Island Zone in Sonic Mania Plus's Encore Mode. When it appears, it seems like Mighty the Armadillo and Ray the Flying Squirrel are trapped inside it. Meanwhile, the Phantom Ruby can be seen floating above it. The player's next course of action is to open Schrodinger's Capsule by pressing the yellow Switch on top of it. This will destroy the capsule, allowing the player to choose between Mighty and Ray as their first partner in Encore Mode. The character the player did not choose will then be revealed to be the Heavy Magician, who runs off with the Phantom Ruby.
- The design of the capsule greatly resembles the Combi Catcher from Knuckles' Chaotix.
- The name is a reference to the "Schrödinger's cat" thought experiment about quantum mechanics applied to everyday objects.
- Though not given an actual name in-game, the internal files on the PC version of Sonic Mania Plus refer to the machine as "Schrodinger's Capsule".