I think Mo shot a half-bait using a lamination plate. When he removed the plate and made sure the bottom halves were in the mold right he used a toothpick or skewer to place a small drop of chartreuse and fluorescent pink raw colorant on the flats created by the plate and then shot his clear plastic into the mold. The drops of colorant get "pulled out" when the hot top plastic goes in giving the effect seen.