McCarthy made the comments during the Packers' recent annual "Welcome Back Luncheon."
"I looked at the tape. They should be confident," Fox said on Monday.
The tape in question is the Packers' 55-14 blowout win over the Bears and former coach Marc Trestman last November.
In his Monday news conference in Green Bay, McCarthy said the comment was meant solely out of respect for the Bears organization. The teams meet Sunday at Soldier Field.
"I don't really talk to our football team the way I talk to the Chamber of Commerce. It was all in fun, but I think it's really just an example of why you shouldn't say things like that in public," McCarthy said. "The reality of it is, it is really the way the game is looked upon. It's a great rivalry. I'm sure a lot worse is said in private about the opposing teams and so forth, but it is with great respect.
"It's the oldest rivalry in the National Football League. In my opinion, I think it's the best rivalry game that I've played in. So playing down there opening day, it's going to be a lot of fun. It's a big challenge."
The Packers led that game 42-0 at halftime after Green Bay quarterback Aaron Rodgers tied an NFL record by throwing six touchdown passes in the first half. Rodgers threw a touchdown on each of Green Bay's first five possessions.
The Packers have dominated the series against the Bears in recent years, winning 11 of 13 -- including the 2010 NFC Championship Game at Soldier Field.
Green Bay travels to Soldier Field -- where it hasn't lost since 2010 -- for Sunday's season opener.