I watched the movie The Martian, and there is a brief scene where there is lightning on Mars. Something about this seems unlikely to me, but I can't remember if it's actually possible or not. Is there actually lightning on Mars?
Lightning has been observed in Mars. However, this is 'dry' lightning, unrelated to precipitation.
This was described in the paper Emission of non-thermal microwave radiation by a Martian dust storm by Christopher Ruf and others.