The mirror is glued to a 12 inch disk of thin plywood with "lazy susan" hardware beneath,
powered by a small DC gearhead motor.
The mirror is not glass, but a plexi-glass type that cuts easily with a scroll saw.
Years ago, the glass mirrors would easily shatter when a lead figure would fall over. Plastic is wonderful!
The simple animation technique is very effective because the skater in the middle of the rink appears to move at a slower rate than those on the edges. See the Lawn Mowing Animation Project for technical details since that project is almost identical except for the mirrored surface, paper mache overlay, and lazy susan.
If the mirror is kept dust-free, only the skaters appear to move.