Below you will find information on visa requirements for an internship abroad in various countries. The information is current as of July 2018 - later changes are possible:

Australia

Canada

New Zealand

USA: In order to obtain a visa for an internship in the USA, you must use a legal sponsor, i.e. you cannot apply for the visa in person at the American embassy in Germany unless the company where you will be doing the internship acts as the legal sponsor itself.
Applying for a visa through a legal sponsor is not cheap. The following companies in Germany, among others, offer to arrange the J-1 visa, i.e. they work together with a legal sponsor in the USA:

College Council

travelwork

intrax