Sixth seed Mitchell beat New Zealand's Craig Caldwell 3-2 on Sunday.
The 45-year-old from the New Forest did not discover his first-round opponent until Saturday, when Caldwell came through a preliminary-round tie.
"I made sure I didn't watch that game. I went back to my room and watched From Russia With Love," said Mitchell.
He told BBC Sport: "It was something I started last year - I don't watch the players I'm due to be playing against."
Caldwell, who hit nine 180s against Mitchell, led 1-0 and 2-1 before the defending champion fought back to secure a spot in the last 16.
"It was too good a test," added Mitchell. "If I'd have lost that, I wouldn't have had a problem with it. Craig really played well."
Being the reigning world champion brings extra responsibilities, as Mitchell has discovered since winning the title for the first time 12 months ago.
"I only did three or four appearances in 2014, compared to the 40 or 50 I did in 2015," he said.
"They were coming up to Christmas as well, so the three or four weeks I usually spend pounding the board for five hours a day weren't there, because I was sat in a car travelling to Manchester, Newcastle or Belfast for the Sports Personality of the Year awards.
"I was only eight or nine rows from the front, which was really cool. I felt like I could touch Andy Murray when he picked up the trophy.
"I got to meet some really nice guys there, particularly (world snooker champion) Stuart Bingham. He rose to fame from nowhere like I did. We were stood there scratching our chins thinking: 'Are we supposed to be here?'
"It was a great evening and it topped off my year superbly."
Scott Mitchell prepared in unusual fashion for the first match of his BDO World Championship title defence - by watching a James Bond movie.