Scooby-Doo and Scrappy-Doo

Where's Scooby-Doo? (1) (5x23)

: 03, 1983

The kids are mysteriously sent train tickets to board the Orient Express, for a trip. But when they get their Scooby's bag is switched with another one, and when he goes in search of his bag full of Scooby Snax, he turns up missing as well. Did the mummy kidnap Scooby, or the spy who stole the fuel formula?