There was also Zach and Travis's helicopter ride in 2007. They were taken to a helipad, presumably within Dreamworld, where ninjas were waiting to help them board. They took a flight around the Gold Coast, seeing the sights from the helicopter. The helicopter then took a low pass over the Big Brother house so they could sit with the door open and wave to Aleisha.
All of these examples at least remembered to limit the HMs' exposure to third parties. Jamie & Chris's trip to White Water World happened late at night, and there didn't seem to be anyone there other than the ninja demonstrating the ride and Big Brother's voice over the speakers. Gaelan & Krystal's visit to Tiger Island had an animal handler there, but it seemed like they were on strict instructions not to ask or talk about the outside world.