The US government has been caught listing Wakanda as a free-trade partner.
The East African country is entirely fictional and exists only in the Marvel universe as the home of superhero Black Panther.
A US Department of Agriculture (USDA) spokesperson said the Kingdom of Wakanda was added to the list by accident during a staff test.
In the Marvel universe Wakanda gives an outward appearance of being poor but is actually rich in 'vibranium' - a precious resource that gives the country great wealth.
The department's online tariff tracker hosted a detailed list of goods the two nations apparently traded, including ducks, donkeys and dairy cows.
The fictional country was removed soon from the list after US media first queried it, prompting jokes that the countries had started a trade war.
The unusual listing was spotted by Francis Tseng, a New York-based software engineer who was looking up agricultural tariffs for a fellowship he was applying for.
He told Reuters that, when he first saw Wakanda on the list, he got "very confused": "[I] thought I misremembered the country from the movie and got it confused with something else."
A USDA spokesman told the Washington Post that Wakanda's listing was added as a test file for staff, and was never supposed to be public .
"The Wakanda information should have been removed after testing and has now been taken down," he said.
They later tweeted: "While we removed the Kingdom of Wakanda from our list of US free trade partners, our relationship will always be strong #WakandaForever ".
