List of Donkey Kong Jr. pre-release and unused content

This is a list of pre-release and unused content for the game Donkey Kong Jr.

Arcade
There are several unused graphics in the original arcade version. One such item is a lightbulb, which may have been an obstacle, decoration, or used in place of the fruits in Mario's Hideout. There are also several graphical leftovers from Donkey Kong that may or may not have been planned to be included in the game, including Mario walking with a hammer, Donkey Kong climbing, Pauline's "HELP!" caption, an Oil Drum, a Sand Pile, the unused Ikegami Tsushinki Co., Ltd. logo, and the full text title of Nintendo Co., Ltd.

Coleco Adam
An extra stage is present in a certain public prototype of the Coleco Adam port of the game. It is first encountered as Bonus 09, then explored again as Bonus 12, and is only enabled via a code: at the number of players screen, press and hold both fire buttons and press 1, 3, 2, 1, 2, 1, 2. If the "Revision 13" message is displayed, that indicates that the exclusive level has been activated for the playthrough. It got relatively far in development and is virtually complete.

The round takes place inside what resembles an old fashioned bakery. Mario stirs around an active oven at the top, constantly picking up pastries from the oven and trying to drop it onto Donkey Kong Jr., who would have to survive several other obstacles, including automated plungers, in order to reach Donkey Kong and finish the round. Each appearance of the round introduces a new obstacle, such as a dough monster, spawned from Mario's pastry, clinging onto poles and platforms, and a stationary toaster flinging slices of bread at the playable character.

Donkey Kong Jr. starts off at the bottom left. This part features a short tunnel containing four automated plunger-like obstacles, pressed onto the ground. This tunnel leads to a section with a toaster and some hanging poles, the latter which can be climbed to access an upper platform. This platform contains a giant bowl and an automated eggbeater moving from side to side inside the bowl. Donkey Kong Jr. would first have to simply pass by the huge bowl in the background and then jump onto several other poles in order to climb up to the eggbeater. It can be stood on just as on a platform and can offer a ride to the following section; by climbing yet another set of poles, Donkey Kong Jr. can reach the top of the area. Here, he would have to avoid Mario by swinging from several hanging poles. Fruit are scattered in between the poles and can be dropped onto Mario to stun him. Donkey Kong lies caged at the end of the round, along with a key to release him.

Coleco had planned to include a new screen each in the Adam versions of both Donkey Kong and Donkey Kong Jr. to take advantage of the hardware's extra memory and multi-loading capabilities, but Nintendo had objections with Coleco taking liberties with their games.