Malthouse was at the helm of the Blues for the first time on Sunday, guiding Carlton to back-to-back wins in its NAB Cup openers.
Now 59, Malthouse sheepishly conceded some habits which once came second-nature had deserted him in the past 12 months.
"I forgot to put the headphones on and was thinking 'gee, I haven't had any messages yet'," Malthouse said.
"Then I realised the guy downstairs was probably screaming because he hasn't had any messages yet.
"I kept asking how long we had to go and there was a clock right there. I probably should've known that.
"You get back on the bike, but you still have to know the rules."
However the notoriously feisty three-time premiership coach bristled when asked how much the game had changed during his short time hanging up the whistle.
"I haven't been out for 30 years," he said.
"It's been 12 months. The game hasn't changed that much."
Malthouse acknowledged it would be some time before Carlton's structures will be mastered as it manages the transition from former coach Brett Ratten.
The admission came despite a first-up come-from-behind win over Greater Western Sydney and a commanding 22-point win over reigning premiers, the Sydney Swans.
Listen to AFL Media's Ashley Browne wrap the second weekend of NAB Cup action:
Malthouse was pleased he now had some vision to demonstrate exactly what he wants from his side, but said it is a work in progress.
"The attempt was there, but we're getting a bit confused with the two game structures from last year to this year," he said.
"We'll certainly need the three NAB Cup games to iron out a few areas of concern.
"There's a whole host (to work on). There's a lot of things that are different (to last year under Ratten).
"I'm not saying one is right and one is wrong, it's just the way I want to do it and that's the way it's got to be.
"We can't have two different game structures and everything else."
James Dampney is a reporter for AFL.com.au. Follow him on Twitter: @AFL_JD
