If anything THIS season of the show is the first time that THEY are creating the issues that could out them. Jane Schmo worked out the thing was a fake without glaring issues, but this one with the guard REALLY should tip Chase off more than even the whole window issue.
And if the actress playing the deaf girl is not eliminated soon (even if in wrong order) they're going to definitely ruin the surprise.
@Shoepie - the reality is at the end of the show Chase (Joe Schmo) will indeed win the $100,000 and any other prizes that may have been given out in the season - even if to other contestants. The ONLY prize not real this year is the bounty hunter contract - he won't really become one.
In short - it's a practical joke yes, but it has a good ending (well unless Chase goes nuclear on them for this being fake, but I can't see that - upset yeah but not a raving mad).