During Martha's breakdown in the party scene, the bow on her white dress is hanging loose when she is being corralled into the bedroom by Lucy and Ted. In the next shot, the bow is done up again.
When Marcy/Martha wakes up after freaking out at her sister's party, she is wearing heavy, perfectly applied makeup. Since she had previously had an emotional breakdown, then slept, this is unlikely.
When Martha is sitting by the lake side her top changes colour from one shot to the next.