According to Us Weekly, a SWAT team from Hungary's anti-terrorism department raided one of the film's production warehouses and confiscated 85 fully functional weapons — the majority of them assault rifles.
According to the magazine, the weapons bore paperwork indicating that they were non-functional, and its not yet known who is responsible for the snafu.
The guns were reportedly flown in via private plane Monday. An official for the Hungarian government told Us that they were wrapped in a parcel addressed "from a company to an individual [in Budapest]."
No matter who's to blame, Hungary's anti-terrorism unit is taking the matter seriously.
"Guns like these are highly illegal to transport even if they were to used as stage guns, which hopefully they weren't," Hajdu Janos and Zsolt Bodnar, the director and deputy director of Hungary's anti-terrorist force, told the magazine.
A spokesman for the film told TheWrap, "We are working with the authorities to resolve the matter and have no further comment at this time."
In addition to starring in "World War Z," which chronicles the aftermath of a zombie war, Pitt also serves as a producer on the film.
Matthew Fox co-stars in the project, slated to hit theaters on December 21, 2012.
Neither Paramount Pictures nor Plan B Entertainment, the production company behind "World War Z," immediately responded to TheWrap's request for comment.