The hole in the blood vial is by far the most mind boggling thing imo
Apparently although it made a good TV, it wasn't actually as damning as viewer would expect - defense failed to prove that the hole in the vial was not part of a standard evidence procedure as piercing the tops of blood tubes was considered to be standard practice while filling them. Broken seal on evidence case with blood was also debunked - members of Avery's defense team recorded breaking into the package during appeal against his rape conviction.