This Illegal Immigration Thing
Back in September and October 2000, I went on "spring break" while an exchange student at the University of the Western Cape near Cape Town, South Africa.
All of the group had student visas glued inside our passports. I recall having quite a long wait that July for my passport to come back to me after I mailed it off to the South African Consulate in Chicago (even now, their Chicago branch office has no website of its own!). Most of us were US citizens, one was German. We spent a couple days in Namibia during our spring break safari, then re-entered South Africa at a different Customs station.
At the border, we had no problem with Namibian border control agents, but at the South African station, we all were given crap because our study permits said "Single Entry Permitted."
So, an additional notice was glued into each of our passports that said "Report to Home Affairs."
For those seven days or so between when we re-entered SA, continued our trek, then came back to Cape Town and started classes again, we each may have been considered "illegal immigrants" of a sort.
Of course, once I figured out where the nearest Home Affairs branch office was, in a non-descript office building in the business district of Bellville (not Belleville), it was pretty quickly straightened out. Single-entry did not prevent you from leaving the country for a few days and then coming right back; it just meant you could not try to come back after your visa had expired.
Yes, I was probably treated better -- and certainly, in an expedited manner -- because I was a white foreigner, an American no less, who had shelled out a couple hundred bucks for my student visa. (My scholarships pretty much covered all the costs, although I'm still not 100% sure I was billed correctly by UWC for the dorm room, but I digress...)
Actually, I was able to leave the Home Affairs office, walk across the street to the local library, hang out for an hour, then walk back over to Home Affairs to pick up my passport, with yet another notice glued inside, with something to the effect of "Landed incorrectly on Visitor Visa" and citing some legislation/code number.
Bureaucracy at its finest!