Sawadee ka, Khun Karaket.
I would like to give some information to you as follows naka:
If you have a Thai Passport, to go to Victoria Falls in Zimbabwe, I think you have to apply for Zimbabwe Visa. For South Africa, there is a visa exemption for Thai Passport (30 days). For further information please see
However, I think you should contact both South Africa Embassy and Zimbabwe Embassy to make sure about the visa and the documents required when you entry the country (for example, air ticket, work permit in Mozambique)