The laws of rugby league were written in 1908 and while most of them have been updated, there are still surprises lying dormant in the pages.

"There was until not that long ago a rule that specifically covered the ball being kicked and deflating in mid air and landing on the crossbar," said NRL's head of football Graham Annesley on Tuesday.

Unlikely as it would seem in the modern day game, these scenarios were once important considerations.

The NRL, intent on keeping the game's rules as relevant as possible, are regularly updating the laws to avoid another head-scratcher on grand final day.

Last season the ancient mutual infringement rule cost Canberra a set of six in the decider when a ball hit a Sydney Roosters trainer.

And as a result, that law was fixed in the off-season to allow the team to replay the play the ball instead of turning it over to the team with territorial advantage.

One of the most unusual ones in the rule book is what should happen if the ball bursts while a player is taking a place kick at goal.

For reference, they should be awarded another kick.

If the player grounds the ball for a try and it's noticed the ball has burst, the try should be awarded, but in the normal field of play a scrum is formed.

The team in possession when the ball bursts gets the loose head and feed.

"Considering that the rules have been in place largely since 1908, they have been regularly updated, but that one last year ... it was clear that it needed to be changed," Annesley said.

"I can't think of a lot of others.

"One of the rules that's in the rule book that people aren't commonly aware of, is if the ball deflates during the game and how play is restarted after a ball deflating during the game.

"But hopefully we won't be seeing that in the grand final."

Australian Associated Press