Checking in was easy except that I had copied an extra digit in the reservation number so it took a bit of time before they found my reservation. The B&B in Nelson had a computer but no printer and no access for my laptop so I couldn't print the info when I made the reservation. Car rental in NZ works by your returning your car before you get on the ferry and then getting another one when you arrive at the other side but it is treated as one reservation. There was also a minor snafu with the reservation since the checkin person in Picton apparently had cancelled the reservation by error so it took a bit of extra time.
These passengers were probably in for a bit of trouble soon after they arrived.