They will ask to see your return ticket. They want to be sure you have a ticket and do not lose all your money later and then can not buy one to leave on time.
Savannakhet just sounds simple. They have an easy system there where everyone gives their application within 2 hours. And you go get the visa the next day within 2 hours. And they do not take appointments. Walk-ins only. So they seem to have a fast system at that one place.