Continuity mistake: When Aria's dad drops her off at school, the camera angle out the passenger window shows her wearing blue jeans. Once she's out, the camera angle changes and she's wearing black Levis.
It Happened 'That Night' - S3-E1
Character mistake: Emily's mom tells Emily that reporters were there to talk to them about "Emily's missing remains." It's supposed to be "Allison's missing remains." (00:17:00)
If at First You Don't Succeed, Lie, Lie Again - S1-E15
Continuity mistake: When Spencer and Emily are done eating pizza, Spencer stacks both their plates. However, when Emily storms off, the plates are unstacked again and now there is a napkin on her plate.
Picture This - S2-E9
Continuity mistake: When Hanna and Caleb are sitting on the swings in the park, the first part of the scene shows nothing in Caleb's lap. However, when it cuts to them holding hands, a pizza box appears. (00:29:10)
Shadow Play - S4-E19
Other mistake: When Ezra takes Spencer's file from the school he takes it from section A-E. Neither of Spencer's names fit into that category.
Continuity mistake: When Fury and Spencer are playing ping pong there is one scene where Fury is holding the ball and Spencer is empty handed, then as the scene progresses Spencer is also holding a ball.
Continuity mistake: When Jason first appears in the show he is played by Parker Bagley and is portrayed as a proper, motivated and well held, wide structured man, but disappears for a season or so, and is replaced by Drew Van Acker, and is now portrayed as a paranoid druggie, with mental health issues, and a lanky skinny structure.
Continuity mistake: Hanna and Alison are at Hanna's home, when the bell rings. Hanna takes a look through the window directly next to the door, and claims it's just Travis. When she opens the door and goes outside, there is no window visible. At least not any kind that could have seen Travis. It seemed to just have disappeared mysteriously. The transition of shots between the set of hanna's interior and exterior is done very poorly. (00:12:10)
Continuity mistake: Mrs Sullivan circles "nosey bitches" on a paper (someone's file) and the circle is overlapped at the bottom. When the camera moves out the circle changes and is disconnected from the top instead.
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: When Allison falls down the stairs her fiancé says "EMILY!"
Suggested correction: He shouts "Ali", short for Allison, not Emily.
Suggested correction: He shouts, "Ali" which is short for Allison.
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."
