The NRL is continuing investigations into how Savage was allowed on as an 18th man on Saturday night, after Canberra illegally enacted their concussion sub.

Raiders coach Ricky Stuart has accepted responsibility, incorrectly believing any reportable foul play could allow it to be activated rather than only after a sin-bin or send-off.

But it hasn't wiped the smile off Savage's face, the 19-year-old happy to have played as his mother Erica, who was at the game "just in case", watched on.

One of the club's hottest young prospects, Savage did not realise the Raiders error when told by Stuart at the start of the second half that he would replace Sebastian Kris and make his NRL debut.

He was then left miffed when ordered off the field 12 minutes later, when NRL officials called the Raiders' ground manager to tell them the cub had erred.

"I was buzzing. I felt like I was high on sugar like a little kid in primary school," Savage said.

"(When I was ordered off) I thought I had made a mistake. I was apologising to them and saying, 'what did I do, what did I do'.

"It was an unusual debut but I will take it. I am sure there will be many more games to come.

"It was a very surreal moment for me, I have been through a lot growing up ... I can't believe that I actually got out there and fulfilled my childhood dream."

The Raiders are certain fullback Savage won't be a small footnote in their history.

A natural speedster, the Cairns product was an under-17s state champion in the 100m and 200m at age 16 with his sights set on the Olympics.

"I was setting my eyes on the Gold Coast Commonwealth Games and then I did a grade-two syndesmosis in Year 11," Savage said.

"I was down in the dumps for a while.

"It was hard coming back and I did my hammy twice coming back from that surgery on my ankle.

"So I just thought I would stick to footy and focus on my transition to coming to Canberra."

Meanwhile Stuart's Saturday night error prompted the Raiders coach to claim the 18th man rule should be expanded to allow for the replacement to be used after a reportable offence.

Ironically, Stuart was the man who pushed the NRL to extend the concussion sub rule to cover for foul play when it was introduced earlier this year, after the initial idea was only covering three failed HIAs.

"If you lose a man to foul play you should be able to enact your 18th man," Stuart said.

"Whether it's put on report, binned or sent off you should be able to enact it. As long as you lose your man."

Australian Associated Press