Field of Bowsers

The Field of Bowsers is an anomaly that occurs in the Castle Grounds. It was reported by Reddit user u/adriank060 on the 8th of July 2020.

Description
When the anomaly occurs, the player will find four or five Bowsers in the Castle Grounds. Their behaviour is similar to that of a Goomba; they wander around aimlessly until they become aware of Mario's presence. When they see Mario, they begin chasing him in a similar manner to how Bowser does in the second and third Bowser fights; they do this at a slower pace than in the fights which allows Mario to flee and they do not stop until Mario somehow gets out of range (i.e. via the cannon), enters a loading zone or dies. At the same time, they attempt to burn Mario with their fire breath. It is currently unknown if there is a way to defeat them.

How to Find It
Due to there only being one recorded case of this anomaly, the method used to find it is largely unknown. However, according to the original poster, their friend who owned the game claimed that it occurred when she finished the game. This may mean that it's a result of a high amount of personalisation due to how much data the AI may be able to gather from somebody who has beaten the game legitimately. It may be a bit of extra challenge given to a player who has proven that they are skilful enough to beat the game.

Theorising


Because DLR only allows the objects from one level to be moved, modified etc. it is possible that in an earlier build of the game Bowser was intended to be in the Castle Grounds. This may be supported by the image on the game's cartridge which depicts Mario fleeing Bowser in a field.

Furthermore, the geography of the field appears to be similar to the Castle Grounds' with Mario and Bowser running on a slope with a steeper slope behind them; this seems similar to the slope just in front of Mario when the game is first booted up. The skybox also appears to be the same. However, the trees appear to be missing.

If this is correct then it is probable that Bowser's presence in the Castle Grounds was cut fairly late into development as it would have happened after the cartridge art had been finalised.