But perhaps the most disturbing passages in "Transcendence," from a strictly visceral point of view, are the images of Dr. Caster dying slowly and painfully after getting shot by the RIFT terrorists. In the film, the deadly bullet has been treated with radioactive polonium, as a kind of grisly insurance policy in case the initial shooting didn't do the job.
The incident is clearly meant to reference the death of Alexander Litvinenko, the former Russian security officer who was poisoned in 2006 with the highly radioactive element polonium-210. No charges were ever brought in the murder, but it's widely believed that Litvinenko was assassinated by Russian spies who dosed Litvinenko's tea with polonium.
Radioactive bullets are indeed a reality, but not quite as depicted in the film. Depleted uranium bullets are used by several military forces worldwide as armor piercing ammunition, due to the material's extreme density. Uranium rounds don't pose the same radiological danger as polonium, but they're still a hazard. Specifics can be found at The International Coalition to Ban Uranium Weapons.