Hey, It's That Voice!: The Latin American dub is full of these, due to the dubbing studio being the same one that dubbed Dragon Ball. Just looking at Shohoku, we find that Hanamichi is Vegeta, Akagi is Nappa/Dr. Gero, Rukawa is Future Trunks, and Ayako is the second Bulma. Other iconic voices are present too, but many of them were switched around for the second half of the dub, making the explanation of who's who into a mess.
Slam Dunk pretty much shares some VA's with DBZ in the original Japanese version too, most notably Hanamichi is Trunks.
The Red Stapler: Many Japanese children started to play basketball just because they read the manga which in turn helped make basketball popular in Japan. Today, Japan's team is usually counted as one of the top teams in the region.
Screwed by the Network: The anime didn't get renewed for another period, so the nationals had to be cut. As a means of compensating, the remaining episode slots were made into a Fanservicey practice match with a few scenes mirroring the nationals.