As to TAR 19, IIRC,, the speculation about Malawi led to speculation about a leg being in South Africa or Kenya; and as I recall, Kenya was having political and other issues right about then. The other element is that, simply because of the uncertainty about where teams were headed, some teams were seen headed towards Phuket (at the airport right?), and we didn't hear more about them until Malawi emerged. This might mean that Phuket itself was a last minute leg change.
If it's TAR 18, I'd have to go back and see as there was a long stretch of that season that there weren't any spotting (after China or India) during filming.