Loud fireworks question?

Fireworks such as these can definitely have an impact on your body, but brain damage and "internal problems" as you state them are not examples. The types of damage that you can have from these would mainly be hearing loss due to the excessive noise. The only other examples would be if you have a sort of strobe piece, and someone with epilepsy, and sensitivity to strobes is watching. This can cause a seizure. Only other option would be if you didn't follow directions while lighting and externally injured yourself. Not brain damage though.