They said it would "rock the house" and give the HMs an experience they would never forget!
I suspect that they had something slightly better lined up, but were prevented because of some unforeseen event, or for legal reasons. We never saw the nominations, and so for viewers it was a surprise that some HMs had been nominated (or so they made out) and that there was a vote (not enough time for viewers to give a real verdict, though Cami Li was a certainty as it happened. We didn't see all the nominations, and had to take it on faith that there were any (on Saturday?).
The HMs were definitely waiting for something to happen when we saw them all lined up on the sofas looking expectant. They didn't seem particularly surprised at the unexpected eviction, so I feel sure they'd been told something. Instead of getting a bombshell, they looked totally unsurprised. It's a disgrace that Channel 5 put viewers through this embarrassing event - it made me cringe to see them pretending it was a big deal. There wasn't even a twist!