suppermariobroth:

Top: In the Super Mario World cartoon, Bowser’s castle has a flashing “Koopa” sign on top of it, which is different from the North American version of the game, where is it a flashing “Bowser” sign instead.
Bottom: However, the Japanese version does match the design of the cartoon castle by also having a flashing “Koopa” sign, due to Bowser’s name being “Kuppa” in Japanese, which was started to be officially transliterated as “Koopa” around the time of the game’s release.

Note that this may be a coincidence rather than a deliberate reference: the Super Mario World cartoon is a direct sequel to the Super Mario Bros. Super Show and the Adventures of Super Mario Bros. 3, where Bowser has always been known as “King Koopa”. The background designers for the cartoon could have gone off the North American version and changed “Bowser” to “Koopa” to keep the continuity; without necessarily referencing his Japanese name. (The English translation “Koopa” predates the usage of that spelling in Japanese media.)
_{Main Blog | Twitter | Patreon | Store | Source: Super Mario World cartoon, Ep. 13, “Mama Luigi”, Source 2}