Keri Belle Conrad wrote an answer about POC Trail Shorts - Men's on August 19, 2014
POC's site also says there is zippered venting on the rear of the short but none of the photos show it. Your review seems to prove that there aren't any, as well. The left leg zipper is for sure a pocket. POC seems to have had a slip up as well on their site, We just got off the phone with them.
The rep we talked to has the Trail and they do not have venting, they are getting their site changed as well. They do make the Trail Vent shorts that do have zipped vents:
We do not have them in stock, unfortunately.
However, A good comparable short with venting:
I'm happy to help you with a prepaid return label and an easy exchange.
Please let me know how I can help and thank you for bringing this to our attention.
firstname.lastname@example.org 801-736-6396 ext 4368
I'm happy to help!