Like with any other genealogy site, including Wikitree, its only as good as the research.
The Pedigree Resource site may or not be sourced, I've been lucky to find several that were sourced with other then Ancestry. Just as on Rootsweb's gedcoms, I have found numerous gedcoms that were sourced.
The collaborative trees can be sourced by clicking on the census and other research lists by attaching that data to individuals on the trees.
Yes, people have made errors. I corrected a James T, Jester at FST twice as to who is father wasn't. FST ID LZ19-QQ6 and here at WT Jester-531. Several trees at Ancestry and originally at FST have him as the son of Levi Jester of Butts County GA. Jester-372. And I know that he is not the the son of this Levi because I have the wills of Levi and his son James. So YES, I corrected that part of the tree, not just once but twice. And if these people were so insistent that a Levi is father of James T. then why not look for a Levi in Delaware where James was born? There is one and he was born the same year as the other.
There are errors on WT also, because even WT is only as good as the research.