Is there anything anyone can point to that precludes the 3 from having killed the kids, or is it more a matter of reasonable doubt? Is there anything that shows actual innocence?
One of the problems with this case is that the only known crime scene was an outdoor crime scene. The time window for collecting inculpatory or exculpatory evidence has long passed (the entire area has been bulldozed and cleared since then), and the way the investigation was handled with a confirmation bias, exculpatory evidence was not considered. They might have found physical evidence of guilt had they conducted their investigation without bias. They never once questioned Terry Hobbs or searched his house, despite Gary Gitchell's acknowledgment that you look at family first (Terry Hobbs left a couple weeks after the murders, about the time they talked to Byers, because his wife's family was accusing him of the murders).
That being said, any new evidence will have to come from items that were collected back then.
Some things that establish reasonable doubt:
1) No physical evidence links the WM3 to the scene.
2) There were no reports that the WM3 exhibited any signs (on their hands / knuckles) of having beaten anybody on the head with their fists to the point of unconsciousness (as Jessie confessed he did).
3) There was DNA in a strand of hair that was matched to Terry Hobbs, and DNA in a strand of hair that was matched to David Jacoby -- Terry's best friend.
4) Six world-renowned forensic experts have concluded that the injuries which were thought to have been caused by a knife (as per the WMPD's presumption / Jessie Misskelley's confession) were the result of animal predation.
5) Police records that demonstrate a clear confirmation bias.
6) Court records that demonstrate a clear bias in favor of the prosecution.
7) Sworn statements from a former prosecutor alleging that a juror had spoken with him regarding the case and had engaged in acts of juror misconduct / lied during his voir dire.