The actor paid for the 350-member crew to travel privately to the film's next shooting location in Scotland along with his partner Angelina Jolie, the couple's children, and several members of their own personal entourage, reports People.
"Three cars suddenly drove onto the platform from the street, pulled up alongside the train and then they all got out," a source told the publication.
"Brad was in one car with some of the kids and Angelina was in another with the others. They were all smiling and looked really happy, but then I suppose it's not every day that a kid gets to have their own train to play with!"
The insider added: "They had a huge entourage of about 20 to 30 people with them."
World War Z execs were reportedly attempting to secure permission from the Falmouth council to film scenes off the Cornish coast.
The film's ensemble cast also includes Game of Thrones actor Elyes Gabel, The Killing star Mireille Enos, James Badge Dale and Antony Mackie. Breaking Bad star Bryan Cranston is also rumoured to be in talks for the project.