It's interesting that Walsh can switch allegiance to referee under the Australian logo when he's not even Australian, after previously refereeing test matches under the New Zealand flag.
Meanwhile, someone like Rodney So'oialo can't change his allegiance and play for Samoa, even though he's Samoan.
Obviously the two scenarios are different but there seems to be an awkward double standard there.
As for the on-field action, we saw a sea-change in the way the games were officiated at the weekend, particularly the two Wellington quarter-finals.
Early in the tournament, I was critical of the way the breakdown laws were being interpreted, believing it was too easy for teams to recycle possession by picking and diving - note "diving" not "driving". The ball carrier would go to ground and his teammates would go in, often off their feet, to seal the ball off and thus maintain possession.
Bryce Lawrence and, to a lesser extent, Craig Joubert took completely the opposite tack. If anything, it went too far in favour of the defending team.
During Sunday's Australia-South Africa quarter-final, the first man to the breakdown could basically seal the ball off, whether you were the attacking team or the defending one.
The Wallabies were having a field day (but they also had to make three times as many tackles and therefore had more opportunity to do so) particularly after South Africa lost Heinrich Brussow to injury.
Wales played it quite similarly to Australia and there were probably more turnovers in those two quarter-finals than there had been in the entire World Cup to that point.
The rugby was probably closer to the intended spirit of the game with the breakdown a genuine contest, though I'm not sure the IRB would have been that happy with the spectacle provided on Sunday in Wellington.
Another more subtle difference is the referees seem to be playing a much longer scrum advantage than we had been seeing in Super rugby. Previously, turnover possession was seen as advantage enough but now we're sometimes seeing play move on a couple of phases before being brought back.
Kelvin Deaker is a former international rugby referee.