Originally Posted by
WoodlandCreature
Yup, exactly that happened to me and a dozen others who were first off the plane a few months ago. Apparently, a tardy AC agent arrived to correctly divert the majority of the passengers, but the group I was with ended up having to fill out forms and pass through border procedures, just as the OP described.
At the airports with separate international departure halls (eg. YVR, YYZ, etc.) on a daily basis they must have all sorts of people who were bumped or re-accommodated for one reason or another and have to go through customers to get back land-side. Not having a passport is the one odd this about a domestic flight ended up on an international gate.