No, this isn't part of that set. It could have been taken at the same time (if it is real), but the rest of the pics were posted in b&w, so IDK. (Liz's eyebrows do look similar in both though, though, and they've gone through a few different looks over time)
The pic isn't a high enough quality to really determine for certain, but it holds up ok as close as I can look in photoshop. The bottom of Ari's hair in the back has a few odd white spots, but if it is photo-shopped it was done well enough that something like that would have been an easy fix for the photoshopper to make.
There's just to many image-quality artifacts to find (or disprove) any photoshopping artifacts. And them teasing this certainly isn't out of line with other pictures I've seen. I just can't say for sure, but I like the pic so until proven otherwise I'm going to go with it being real.
I would like to think this is real as well, but I don't think it is. If you look very closely at the tips of their noses, you can see a bit of blurring/distortion, probably caused by the eraser tool or something. And if you look at the flat edges on their noses and top lips, I'd say they were probably pressed against the cheeks of someone standing between them, or the person who made it just did a bad cut job.
~ Zooey Deschanel ~ Taylor Swift ~ Emma Stone ~ Kristen Bell ~ Alison Brie ~ Victoria Justice ~ Amy Adams ~ Jenna Fischer ~ Amber Heard ~ Olivia Wilde