Harvey was spotted standing behind the goals as North went through its paces ahead of Saturday's crunch match at Etihad Stadium.
Scott said he was amused rather than bothered by his counterpart's secret attendance.
"We can call it a closed training session at Arden Street, but half of North Melbourne watch it," he said.
"I don't know what he thinks he's going to get out of it ... you don't often see another senior coach at your closed training session. You usually send your scout.
"It was a complete surprise. It wasn't until one of the players said, 'Is that Mark Harvey?' I looked across and said, 'Yeah, it is'."
Scott said coaches often worried too much about onlookers at training sessions and, with a gentle swipe at Harvey, noted that North Melbourne officials had been kicked out of Fremantle Oval before.
"I think it has absolutely no impact on the game," he said of the tactic.
"He (Harvey) can come down next week as well if he wants."
Speaking from Melbourne's Wesley College on Friday afternoon, Harvey argued he thought North's session was open because of the number of people watching.
"I was in a khaki outfit. I was actually looking at a car and it wasn’t a Mazda," he joked.
"I just happened to look over and they were training, so I just wandered across for 10 minutes to have a look and then wandered back.
"I didn't break any ethics and there wasn't any malice in it."
Meanwhile, Scott has thrown his support behind twin brother Chris' senior coaching prospects.
Chris Scott, a dual premiership player with the Brisbane Lions, is in his third year as an assistant coach to Harvey at Fremantle.
Highly regarded, he is understood to be a candidate for the position vacated by Mark Williams at Port Adelaide.
"I suppose I have mixed feelings about that," Scott said. "I'd be absolutely rapt for him if he got the opportunity to become a senior coach, but I'd be pretty disappointed for North's prospects.
"He'd be a worthy adversary. He's a very capable coach and I think Fremantle value him very highly.
"It would be terrific for him as a brother but as a senior coach at another club, it would be tough coming up against him. He knows his stuff."
