Martyn Goddard If you don't have an exit booked from Thailand within the duration of a visa (
*****
days) and you are refused entry by Immigration then the airline can be held responsible and have to return you at their cost so yes they can and have refused bording under those circumstances. Just book a train or bus ticket to take you to Laos before the end of the visa term and show that and you might also need it at Thai immigration, you don't have to use it if you get the extension but it's probably the cheapest option. You can just wing it as most people do and don't have problems but do you want to risk it?