Revealing mistake: In the parking lot shot, one patron of the Leisure Center warns an arriving patron that Brittas is back, prompting the arriving person to reverse their car out of the parking space. However, note the arriving patron's hands - his car was already in reverse before he was spoken to.
Factual error: When Helen tells Laura she's trying to quit all the pills that she takes to deal with Gordon, she starts listing them off. "The Valium, the Diazepam, the Librium..." Valium and Diazepam are the same thing. (Valium's the brand, Diazepam's the generic).