Chez Mammy - S3-E15
Revealing mistake: When Cathy and Gaston return to the house to find Betty, Father Damien and Annette Curtain high from the chocolate brownies, she asks where Mrs. Brown is and she tells Cathy that she is upstairs wandering around since she is high. Cathy then tells her to come back downstairs and Mrs. Brown replies a few seconds later saying she is coming back down and flies down the stairs in the chair lift. Before Mrs. Brown comes back down, she can actually be seen sitting in the chair lift at the top of the staircase, from the moment where she tells Cathy she is upstairs to the moment where she says she is coming, waiting for the cue to come downstairs.
Mammy Sutra - S3-E13
Visible crew/equipment: After Dermot has explained to Mrs. Brown what Acme Frozen Foods is the second time, Mrs. Brown asks Maria if she understood what he said to which she replies "Yeah. Did you?" The shot then cuts to Mrs. Brown jokingly saying "No. What was it?" and a boom mic can be seen at the top of the screen whilst she is saying the line.
Christmas Special: The Virgin Mammy - S2-E8
Continuity mistake: When Kathy is talking to Mrs Brown regarding her parties, Kath's hair repeatedly goes from normal hair to what looks to be clip ins.