Careful What U Wish 4 - S1-E14
Other mistake: During the scene after the fund raising dance when Lucas offers to take Hanna home, she calls him Ian when she says that she is going home with Emily and Spencer. Even if she says "I kind of promised them", the subtitles say Ian.
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.
In the Eye Abides the Heart - S7-E15
Other mistake: In this episode, and a few episodes afterwards, Aria's phone's battery is at 76% every single time she looks at her phone, until finally dropping to 70% in episode 17 of season 7.