When Carver and Helen are shooting clays from the back of the yacht, neither one of the shotguns produces any recoil. Shooting clays is typically done with a 12 or 16 ga shotgun - both produce noticeable recoil. Also, Helen's gun produces no muzzle blast when fired.
When Helen gave Cat the Bank note it was folded, When Cat went to look at what was giving to her it was crumbled.