The train, packed with 500 people, left on a round trip to Hindon, as part of the Cadbury Chocolate Carnival.
Cadbury World manager Kylie Ruwhiu-Karawana said the young passengers disembarked at Hindon to find a Crunchie treasure chest, but that treasure had to be guarded closely on the return trip.
A band of outlaws, bearing a surprising resemblance to members of the Mosgiel Pony Club, attacked the train and only some quick work by the sheriff saved the day.
''Everyone remembers the old ad,'' Ms Ruwhiu-Karawana said.
The carnival brought it to life every year.
She said this was the eighth year the trip had been held.
Taieri Gorge Railway chief executive Murray Bond said yesterday's trip, and another on Thursday, were both sold out within a month of tickets going on sale in early May.
