Can a blood clot in the lungs travel to the brain?

Normally not but if someone have a hole in the heart or in medical terms patent foramen ovale which is like a congenital curtain between left and right chambers of the heart , then the clot can travel to the brain and give you stroke . Otherwise if someone is immobilized for a long time after a embolism , the underlying factors can predispose to having a brain stroke .

Not the usual path, however possible in the presence of heart structural abnormalities. Much more common directly from the heart with arrhythmias.