Nightmare in Dream Land was the last game to credit Shinichi Shimomura, who co-directed the game with series creator Masahiro Sakurai, as a staff member. Shimomura previously served as a regular map designer for the Kirby series and directed Kirby's Dream Land 2, Kirby's Dream Land 3, and Kirby 64: The Crystal Shards. Exactly what became of Shimomura after Nightmare in Dream Land is unknown, with many fans speculating that he retired from the video game industry and/or passed away.
In 11/2002 interview with the game's designer Teruhiko Suzuki & general director Masahiro Sakurai published in Nintendo Dream, Suzuki stated that his team began the game's development last summer, by making prototypes to decide if Kirby's sprite should look bigger or smaller than how he appears in Kirby's Adventure. Sakurai expressed uncertainty about the graphics, including the backgrounds. He wanted to improve them so "today's gamers wouldn't find them embarrassing", and the developers ended up redesigning the backgrounds from the ground up in CG. On the other hand, he felt confident that Kirby's new sprite looked "just as good as something you'd see in a modern game."
The blue alternate palette of the mid-boss Phan Phan (replacing Rolling Turtle from the original NES game) bares a slight resemblance to the Pokemon Phanphy, whose name also incorporates "phan" from the word "elephant".
The color on the game's PAL boxart is noticeably darker than the North American boxart. Because of this, Meta Knight's cape is hard to discern against the cover's background. Kirby and the game title are also a darker shade of pink, and the Nintendo Logo is next to the game's rating box rather than underneath it.
In the remake of Kirby's Adventure, Kirby: Nightmare in Dream Land, the official Japanese website for the game had many screenshots that were taken at a previous point in development. Poppy Bros. Sr. appears in one. The image shown shows that his sprite was originally going to be similar to his sprite from Kirby Super Star.