Those guys in red masks. I don't even... My brain doesn't know what to do with that information. Honestly, after seeing it on TV I think I tried to push it out, thinking it was a momentary advertisement for some other show where they weren't just some random, out of place element but made perfect sense. It's just sort of a moment of, "How... Huh."
When I first saw them on the TV they reminded me pretty strongly of how Anonymous would wear those Guy Fawkes masks during protests, and seeing as Rising Tide has been described as hacktavist and their logo is a similar red color... But that's doubtful as they look like a very serious group in the trailer (all perfectly dressed and very professional/serious in their mannerisms, not anything like what we've seen from Skye). Plus I don't they would have the brainwashed woman go after a bunch of Rising Tide protestors. It doesn't make sense, plot wise, to do something like that so early in the seasons when we're still trying to really establish what Rising Tide is and where it lies on the big line of "Good" and "Evil".
Looks like a Coulson heavy episode, though, which should prove interesting! Let's face it, the guy is the main draw of the series and the closest it comes to a single headlining character but so far the episodes themselves haven't really focused on him.