What are the four Dutch exclusive cards in Munchkin Koethulhu?
According to this post on the Steve Jackson games forums, the four Dutch exclusive cards are Verwilderd, Inburgeringscursus, Ontlastingsdienst, and De Dodenrit.

Note that the linked post listed one of the cards simply as Dodenrit while this image on BoardGameGeek shows it as De Dodenrit - so I can't guarantee the listed names are 100% complete, or if there a slight difference in versions between the two sources.