What should I do if the online form requires proof of departure date but I haven't booked a flight?

The TDAC form for entering Thailand does not require a departure date. Users can leave this field blank as it is not marked as mandatory. Those without flight reservations can consider alternative transport options like bus tickets and use dummy flight applications if necessary. There seems to be some frustration over unnecessary fields in forms, but it's noted that entry dates must be within three days of submitting the form.