In a surprise move, midfielder Daniel Connors was named as the Tigers inaugural substitute 90 minutes before the game, while the Blues also decided to go with a running player in youngster Kane Lucas.
After countless laps of the boundary line, Connors was subbed on at the 13-minute mark of the third term to relieve an underdone Nathan Foley, who had been battling a bout of gastro throughout the week.
Connors had little impact with just the six touches in the quarter and a half he played and Hardwick admitted he made a mistake by playing Foley and naming Connors as a substitute.
"I made a blue to be perfectly honest," Hardwick admitted after the 20-point loss.
"Axel Foley had gastro all week and I sort of half forced his hand to play which, of course, cost us in the end. He just couldn't go on and had vomiting and diarrhea.
"So that was my blue but Dan has obviously had an interrupted pre-season also and we just tried to get some experience on the field up to half time. "
To add to the complexity of the situation, Carlton utility Jarrad Waite collided with Richmond defender Alex Rance just before half-time and was substituted off the ground with midfielder Lucas coming on to replace him.
The extra runner in the Blues midfield caused a headache for Hardwick, who had key position player David Astbury without an opponent.
"The funny thing about that was Carlton lost a key position bloke and brought on a runner, we lost a runner and had an extra key position bloke.
"Dave didn't actually have a match up by the end of the game and we were just trying to figure out where he can play.
"They had [Shaun] Hampson for a taller player down there, so we were basically left with an extra key position guy and a runner short on the bench.
"It sort of killed us in the end but my blue for playing Foley, he was far too crook."
Carlton coach Brett Ratten decided to use his substitute when Waite received a knock rather than have his bench stretched to just two interchange players.
Waite eventually recovered and could have returned to the field and Ratten admitted he wish he had the luxury of time to give his utility time to recover before taking him completely out of the game.
"Maybe with a bit more time, Jarrad might have been able to come back on, but that's the rules. You deal with it," Ratten said.
"We spoke about it, that we'd give the doc five minutes - we can adjust -and then we'd see what we could do from there onwards.
"We had the philosophy going into the game that we'd use it not as a tactic to add run to the game but as a cover for injuries so we didn't get caught out. It was more of a safety-net for us and we had to use it fairly early."
