If you take a charter bus out of town, you need to make sure the bus has "authority" to have you on board. This is really for your protection. If they have authority, you're ensured that the company has insurance to cover things should there be an accident.
You can check on their authority one of 2 ways. Ask the driver for their DOT number.
1) Call the Oklahoma Corporation Commission at 405-521-2211 and ask for their Transporation Department. They can take the DOT number or name and check for you.
2) You can check yourself by going to the below link. I like using this site because you can plug in the company's name and find out a lot of information.
This is a federal website that, among other things, provides links to Federal Motor Carrier Safety Administration data. Go to the bottom of the page, middle column ("FMCSA searches"). First thing to do is click on the top link ("Company Snapshot") You can search by name or DOT number. You can also check their licensing and insurance by going to the third link on the list. If they can't be found, that should send up a red flag.
Also, it's a good idea to look at the bus BEFORE it comes to pick you up. The church group got quite a surprise. On the company's business card it said "latest equipment ".... they say the bus was 30 years old!