The owner of the gun shop asks the woman if she has a license to own a firearm. Also, later in the episode, mention is made of the woman's husband having a registered .38 revolver. The state of Florida does not register firearms, nor are you required to have a license to own one.
When the unsub hears the announcement about the shootings over the radio in her car, the radio is tuned to 98.1 FM. There is no radio station at 98.1 FM in Tampa, but this is deliberately fake (just like the 1-800-555-0140 hot line).
In Shelley Chamberlain's bathroom, she opens a pill bottle and sees that it is empty. She throws the empty bottle into the sink. Instead of an empty bottle sound, the sound effect is pills dropping into the sink. When she throws a second empty bottle into the sink, the correct sound plays.
The turn signal heard in the Unsub's Subaru hatchback is a turn signal used in Chevrolet (and other GM) vehicles.
While the unsub is approaching the police checkpoint, there are several mountain ranges at various angles. There are also large hills in the background when the unsub's husband is getting out of his car to enter his house. Florida does not have topography like this, aside from Space Mountain in Disney World.
When the unsub's husband is getting out of his car to enter his house, you can see large hills in the background. Florida has no topography like this.
When Shelley confronts her ex-husband, Don, at his house, he tells her she's not supposed to get within a certain number of yards of him, meaning that he has taken out a restraining order against her. Yet once the team determines that Shelley is the unsub, they waste a lot of time trying to figure out who her target is. In researching Shelley's background, Garcia should know right away that there is an active restraining order against Shelley, yet the restraining order is never mentioned by any member of the BAU.