Corrected entry: They're often trying to figure out who is on the plane, but it would seem pretty easy to determine just by asking questions about innocuous things, such as the layout of Sydney airport, what food/movies they had on the plane, a description of the check-in counter, etc. There are probably hundreds of possible questions that someone who wasn't there wouldn't know.
Japan-Games
22nd May 2008
Correction: And how much would you honestly notice about the layout of an airport, or the check-in counter (which look pretty much identical in every airport I've ever been in)? There are airports that I've arrived at or departed from, but I couldn't tell you much about the layout - you just follow the signs; you don't need to learn where everything is. Movies? All they have to say is that they didn't watch any or they were asleep so they don't remember. Food? Early on there's still food remaining from the plane, so easy to determine what was on the menu. Who were they sitting next to? Given that the majority of the plane's passengers died, would be relatively easy to simply claim to be sitting next to one of the fatalities. An infiltrator could work out a plausible answer to just about any question that they might be asked, particularly as initially the survivors have no reason to suspect that there could be anyone there who wasn't on the plane, allowing them ample time to research their story.
Tailkinker ★