For most visitors, the useful Mokpo bus facts are payment, transfers and who to contact when something goes wrong. Mokpo City currently lists the standard local-bus adult fare at KRW 1,700 in cash or KRW 1,600 by transit card. Seat buses are KRW 2,400 cash or KRW 2,300 by card.
A transit card is usually the easier choice if you expect to change buses. Mokpo City says one free transfer is available between Mokpo city-bus routes within 40 minutes, except when transferring to the same route. On wider Mokpo–Sinan–Muan connections, a regional transfer may require paying the fare difference.
The city says transit cards are sold at roughly 400 convenience stores and general merchants, and card-enabled credit cards or some mobile-payment functions may also work. Do not assume a foreign-issued bank card will be accepted as a transit card; if your card does not work, buy or load a local transit card before boarding.
If you leave something on a bus, the operator depends on the route. Mokpo City's current page lists separate lost-property/dispatch contacts for city-operated routes and the private operators. Save the route number and approximate boarding time before calling; that gives the operator a practical way to trace the vehicle.
Before a late trip or a regional connection, check Mokpo's transport information center for the live route and final service rather than relying on an old timetable screenshot.