The morning after Mavis' first night home she is walking down the street in a dark shirt, zipper hoodie, and jeans and is carrying a diet coke bottle. The next scene shows her sitting on a park bench typing on her lap top wearing a striped shirt, and next to her you see a shopping bag with half of a red star visible to viewers, indicating that she went to Macy's. Then in the next scene (which is presumably the same day and same trip, as she is getting ready to see Buddy for the first time that night) she is back in her dark colored shirt while she is getting a pedicure. She doesn't wear the striped shirt and go to Macy's until the following day (the day of Beth's concert when she goes to Macy's to buy her outfit). The scenes are out of sequence.
After Mavis gets her nails done in dark blue, she is at KFC writing when Buddy calls her. Her nails are blue during the entire phone call, but the right before she hangs up the phone they are suddenly unpainted. In the next scene they are back to blue.
The highway signs (I-35, I-535 & US Hwy 53) outside the Hampton Inn that Mavis checks into would seem to place Mercury, MN in the Duluth area, but the strip mall next door features a Chuck E. Cheese's, Raymour & Flanigan Furniture, and Liquid Ice. The nearest Chuck E. Cheese's are several hours away in the Minneapolis area. Raymour & Flanigan and Liquid Ice are chains only found in the Northeastern US (PA, NY, New England), and a highway sign seen after the interstate signs at the hotel is a New York State Route 35 sign supports that.
When Charlize Theron is sitting in KFC, the cup says KGC from one angle and then KFC from another. While thought to be a mistake, the cup reads "KGC" because for a short while, Kentucky Fried Chicken tried to rebrand itself as Kentucky Grilled Chicken, offering a healthier option to their original fried chicken. The cup bears the new, short-lived KGC logo.
Mavis orders a Maker's Mark and then gulps down 2/3, then when she goes to drink again, the glass is full again. However, Mavis pours more of the Maker's Mark into the glass and finishes it, she then proceeds to grab an already poured full glass of wine from the table.