Driver Stephen Jennings and passenger Rachael Rivera were arrested after the unusual items were found in their car on Wednesday morning in Guthrie, Oklahoma.
They were initially stopped after police noticed their vehicle’s licence plate had expired, but officers soon noticed the timber rattlesnake in a box on the backseat.
Mr Jennings, 40, then told police he had a gun in the vehicle and police discovered that the car was stolen.
“So now he’s got a rattlesnake, a stolen vehicle, firearm, and somebody under arrest,” Guthrie Police Sergeant Anthony Gibbs told local broadcaster KFOR-TV.
After a further search of the car, police found an open bottle of Kentucky Deluxe whiskey and a container of “yellowish powder” that was labelled “Uranium.”
Mr Jennings told officers he was trying to create a “super snake” after the uranium was discovered, ABC reported.
“When that happens, of course, we call in a company that deals with that specifically, and it’s taken safely into possession,” Mr Gibbs said. “The uranium is the wild card in that situation.”
Bodycam footage from the arrest shows one officer spotting the snake in the backseat, before saying: “That sucker is huge.”
Timber rattlesnakes are highly venomous and their fangs are long enough to penetrate clothing and boots, according to the Ohio Public Library Information Network.
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Mr Jennings was charged with possession of a stolen vehicle, transporting an open container of liquor, operating a vehicle with a suspended license, and failure to carry a security verification form, ABC reported.
Ms Rivera, 30, was charged with possession of a firearm after a former felony conviction.
Mr Jennings had a valid lifetime hunting and fishing license so possession of the rattlesnake was legal.
The pair were not charged in connection with the uranium as officers are still looking into a potential motive.