Odd situation: My 5 year old son has dual Thai-American citizenship. His American passport is valid, but his Thai passport has expired and we are having trouble renewing his Thai passport due to problems with registering address. We will travel outside of Thailand and return. What problems are there if he leaves Thailand and enters Thailand with only his American passport? He has traveled outside of Thailand but in the past he stamped in and out of Thailand with his Thai passport. He does not have a departure card in his American passport, or any entry or exit stamps.
TLDR : Answer Summary
The user is concerned about the implications of traveling outside Thailand with their son, who holds dual Thai-American citizenship, and returning with only his valid American passport while his Thai passport is expired. Comments suggest that the son may face difficulties exiting Thailand since he originally entered on his Thai passport, and there's a risk he may need appropriate consent from his mother. Additionally, it's noted that children cannot be fined for overstays, and the best course of action would be to ensure his Thai passport is renewed before future travel.