User blog comment:XGlass Reflection/Ch. 54 Review~ Erwin of the Rebellion/@comment-24278139-20140208224253/@comment-12642484-20140210013423

Levi and Mikasa probably entered through the roof while Reeves and his men were outside, while Connie and Sasha stayed back on the roof. When the men entered the warehouse again, Jean and Armin were already freed (they suddenly stood up, so it is logical to conclude this). Also Mikasa was shown to lie in ambush behind a crate.