There is the requirement that you have proof of exit transport when entering Costa Rica. I had put off dealing with until two days before our departure to Costa Rica.
I thought that I could get an online bus ticket from San Jose, Costa Rica to David, Panama. Nope. I could not even get one by calling the bus company. It has to be in person and you show passports.
My initial solution was to buy a plane ticket from San Jose to Panama City, Panama. This would at least move us in the direction we want to travel. What a surprise to find out that Travelocity would allow me to buy the tickets and then cancel them, at no charge, within 24 hours.
At the Southwest Airlines boarding gate desk in Houston, they did check our documents to verify that we had exit transportation from Costa Rica. At customs in Costa Rica, they did not ask for proof, so the airlines monitor it.
We flew to Costa Rica, cancelled the flight to Panama City, and the next day went to the bus station to buy our tickets in person.
In the future, I will figure things out a little quicker, as I do not expect to fly again until we leave South America. Panama to Columbia will be by sailboat or ferry as there are no roads connecting the two countries.