Chord (Sam) filmed a scene with Harry (Mike), Naya (Santana), Dianna (Quinn), Blake (Ryder), Jacob (Jake) and HeMo (Brittany) where around the same time Chord tweeted it, Naya tweeted a picture of Santna's fake ID
Quinn and Santana are confirmed to use fake ID's, which are presumably to get into the bar (idk if the others go but Quinntana defs go together), they drink together, get drunk and sleep together. So Quinn does is since she's drunk. Or something like that
*BONUS SPOILER*
Out of the five couples singing in 'We've Got Tonght' (Finn + Rahcel, Kurt + Blaine, Jake + Marley, Quinn + Santana and Artie + Betty [Betty = new character introduced in this episode, played by Ali Stoker from TGP2]), four will go 'all the way' in the hotel room.
So 4/5 of them will have sex, Marley told Jake in Sadie Hawkins she wasn't ready to have sex, so I doubt she'd do it with him a few episodes later.
Also in 4x15, "Santana’s snooping results in two shocking discoveries" so I don't know what this could be, but someone is meant to be preggo, so one could be that, not sure on what the second could be but maybe she doesn't remember kissing/having sex with Quinn since she was drunk.. so?