The madness of this crowd figure may well never be resolved. I know of the following numbers and sources:
- Official NRL 2005 Annual - published late 2005 - 16,258 (also reflected on rleague.com and Wikipedia)
- League Express Magazine - published three days after the game - 15,400
- The ABC of Rugby League - published September 2006 - 15,400
- 100 Years of Rugby League - published 2007 - 18,000
Given that two reputable sources (League Express, ABC of RL) give a crowd estimate of 15,400, and that an "official" volume in 100 Years of Rugby League gives a different figure than the "official" 2005 Annual (and also given the horrendous track record with regards to accuracy the NRL Annuals suffer), I am inclined to think that all three figures are estimates - with the 16,258 figure a sad attempt to come across as an exact, official count.
I can only guess that something went wrong with the counting on the day and no official number was available, hence estimates were relied upon. And it's for that reason it seems sensible to go with the most conservative estimate (and also the estimate provided by League Express, which would have almost certainly been given by a reporter at the venue at the time).