They keep referring to collecting DNA from the hair shaved from the girls hair. You cannot extract DNA from a cut hair only a pulled hair as it is only found in the hair root.
When "Mina" was found 14 months ago she didn't let anyone take a cheek swab (for a DNA test) as she was petrified and hence the CSU bagged the hair she claimed to have cut off with the straight razor. It would have been more sensible to actually test the DNA using the blood on the razor blade.
The blood on the razor was the real Mina's blood as well, so it wouldn't have made a difference to the test results but it's improbable the NYPD would compare a strand of hair when they have traces of blood.
The 220-lb body is said to have been dismembered before being sent through the chipper. If that had happened, some of the construction crew should have seen a huge pool of blood on the ground somewhere nearby long before the wallet was pulled from the chipper.
No explanation for how the killer (or any of the suspects encountered during the story) could have lured the victim to the construction site.
Holmes says the chipper's feed chute is not large enough to have inserted the body whole. But the large foreman sitting in front of the flaps has plenty of room around him to crawl inside easily.
While rummaging through the mother's SUV around 40:40, Watson talks about her father "...back when he was still putting his name on his own work," which doesn't actually make sense. He wouldn't put anyone else's name on his own work; nor would he put his name on anyone else's own work. What she meant to say was "...back when he was still putting his own name on his work."