What Goes Around, Comes Around - S3-E18
Plot hole: Tess sends Jack an airline ticket to visit her in Australia. The ticket reads 'From: Eureka, Oregon, To: Sydney Australia.' Seems odd that a commercial carrier would have a terminal in the most secret town in America. Eureka is a town created by the US government for its top scientists to experiment with new technologies. It is made nearly invisible from the outside by giant holograms. Very few non-residents even know of its existence.
Suggested correction: There's nothing to suggest Eureka has a terminal open to the public or other commercial airlines. In fact, the airline is named CircumGlobal which is probably not a coincidence that it shares part of its name with Global Dynamics. It could be a private airline only for Eureka staff and citizens.