Bonus are featured in several tankōbon volumes of the Dr. Slump manga. Those are cards, short documentaries, or games.
Hoyoyo cards (Volume 1)
Volume 1 features seven collectible Hoyoyo cards, which have to be cut from the manga pages.
This Is How I Draw Dr. Slump, Y'all! (Volume 3)
Main article: This Is How I Draw Dr. Slump, Y'all!
Scattered in volume 3, are the pages of a short manga documentary about the process of how Akira Toriyama gets each chapter of the Dr. Slump manga done.
Dr. Slump Ho-yo-yo Resume (Volume 4)
Volume 4 features the Penguin Village ID cards of various characters of the series. (Note that Arale's features a mistranslation: it should read "3rd of Flying Fish, 1967", which is part of her cover story; she was completed on the same date in 1980. Her age being given as "14", however, is a mistake on Akira Toriyama's part, perhaps because he had not yet decided which sea-creature corresponded to each month; she should still be "13" as of April 1st, 1981.)
Character Creation (Volume 9)
Volume 9 features short stories about the creation of a few characers in Dr. Slump.
One day with Akira Toriyama (Volume 12)
A photo documentary that shows Akira Toriyama's typical working day in 1983. It includes the author's comments.
Board creation (Volume 17)
In the pages of Dr. Slump volume 17, Akira Toriyama explains how he creates boards for his manga, with a board from Dragon Ball as an example.
Various games and manual activities are featured in the pages of the Dr. Slump manga.