As the "guests" arrived they were frisked and had their identities checked by a police officer dressed in a dinner suit. After having their make-up done, the contestants waited backstage where they could hear the sound of a taped studio audience. One by one they were called on to the stage, along a red carpet, through a cloud smoke and straight into the hands of two awaiting police officers.
This event, which is already being decried by civil libertarians, will be broadcast on the UK's Channel Five (the same fearless bastion of the public's right to know that recently got David Beckham's alleged lover to masturbate a pig on air.)
In one of Pratchett's Discworld novels, Captain Carrot of the City Watch sets up a trivia machine in an infamous bar. The questions were all along the lines of "who robbed whatsisname's house on the night of whenever..."; they made many arrests before the crooks caught on.
Apparently they do it, with substantial success, in the US all the time. The movie in question I think was either Serpico or The French Connection (probably the latter).
I'm sure that setup was used in a movie once, wasn't it? Wasn't a game show - something else, but the basic idea's the same...