Continuity mistake: When Lieutenant Tanner has all the Liars lined up at the station, she says that she's giving them a chance to tell their side of the story before her side becomes the only side. As she says this, Aria can be seen scratching her head in the reflection behind Tanner. In the next shot however, both Aria's arms are suddenly folded.
Character mistake: Ali calls Emily "Hannah" when getting to the romantic spot that she set up.
Suggested correction: Ali doesn't call her by any name. I think what you're hearing as "Hannah" was the line "and if" (and if this is our last chance of freedom). Or before when she said "I had a dream."