Wait, no one is going to myriad of physics problems beyond just the position? Hawkeye would need super powers to support the torque generated from an adult male resting on the arrowhead. Not to mention the arrow itself.
Furthermore, does Antman have the strength necessary to grip the arrowhead as it zips out of the bow? Otherwise he's in for a horrendously bloody wedgie.
Let's say he does hold on. Average compound bow tops out at about 200N. Antman weighs about 150 pounds, or 68 kg. That arrow is accelerating at just under 3 m/s^2. Even Downsyman could dodge that if gravity didn't pull it down first.
We really should get a kappa emote for the board. They really shouldn't have specified that Antman kept his mass as he shrunk. Just come up with some other gimmick like the suit gave him super strength inversely proportional to his original size, something like that.