I used to be on a South African military forum many years ago, some of the guys there talked of tales of Rhodesian soldiers driving across the border to South Africa with their equipment and vehicles.
While these tales are mostly just that, tales, there were a number of Rhodies who went to SA and joined the South African Defence Force. I'm pretty sure there was a particular unit of the SA Army that had many experienced former Rhodesians serving in it, I just can't recall the specifics.
A good many Rhodesians saw the war as one of atheistic communism against Christian capitalism and I believe a large number of them felt the fight was not yet done when Mugabe took over. When he did take over, the Selous Scouts were just shut down because he hated them so much. Unlike other units of the Rhodesian Army who were at least allowed a decommissioning parade, the Scouts just "ceased to be". I would not be surprised if a number of them went to South Africa to continue the fight against the "godless communists".
Interestingly enough, there's a few good vids on YouTube such as this one of a Rhodie Army Chaplain talking about the situation in the late 1970s
Rhodesia Unafraid part 1 [ame="http://www.youtube.com/watch?v=TYL6aTK3k6Y"]Rhodesia Unafraid (Part 1/2) - newrhodesian.net - YouTube[/ame]
Rhodesia Unafraid part 2 [ame="http://www.youtube.com/watch?v=e7YV_0XEY8U&feature=relmfu"]Rhodesia Unafraid (Part 2/2) - newrhodesian.net - YouTube[/ame]