Here is where to find each of the bus tickets in the game.
DOWNTOWN BUS TICKET:
After you find the first of the Dutchman's treasures, talk to Mr. Krabs when he goes in the Krusty Krab kitchen. He will give you a Downtown Bikini Bottom bus ticket.PS: When SpongeBob challenges Squidward to a race to the Krusty Krab, loose to him on purpose. It is really funny!!!
JELLYFISH FIELDS BUS TICKET:
After you have gotten the second treasure from Sandy's Treedome, look around Resident Row. A jellyfish should be swimming around in Patric's backyard and it will have the ticket. Catch that jellyfish and nab that ticket!!!
CHUM WORLD BUS TICKET:
At the top of Jellyfish Cliffs(The place you ride all of those giant jellyfish) you will find Plankton's missing Chum World Clown. Chase him around and get him to hand over his Chum World Bus Ticket.
GOO LAGOON BUS TICKET:
About in the middle of the game, Larry The Lobster will be standing at the Goo Lagoon Bus Stop. Convince him to hand over his extra bus ticket by giving him 50 jellyfish(game total) to make his favorite snack. Happy hunting!!!