Wave race is one of the most interesting beta for the nintendo 64, because they changed completely the original concept. In fact,The Shoshinkai 95 build, that we can see in the screenshots in this page, featured motor boats instead of jet skies, unlike the original wave race for the gameboy. The track design is very early, even though we can see some resemblances with the final versions, such as the stage with the houses that looks like a beta of the secret track of Venice.
The number of competitors was greater, perhaps because the advanced physics of the sea had not yet been implemented in its entirety and thus the engine allowed more polygonal models on the screen at the same time. Of course, the main gameplay (pass on the side of the buoys) wasn’t created yet, but the motorbots were capable of real-time morphing, as you can see in the video linked in this page. At E3 1996 Nintendo finally presented the version of the game that we all played all these years
[English translation by yota]