At the end of the episode Jane, her mom, and Maura are sitting in the bar when Maura's mother comes in. A waiter brings a milkshake to the people sitting at the table next to our ladies and they discuss their love of milkshakes. Less than a minute later as the camera pans out the "milkshake table" is now clean and the people gone.
Frost declares that he has found a second shell casing, but no first shell casing was shown to have been found.
The parrot is referred to as a "he" in numerous occasions. A true animal lover like Korsak would have known that it is actually a female as the patch above its beak is brown (female) and not blue (male). Budgerigars is one of the easiest species of parrots to separate male from female.
The bullet that Isles removes from the dead body is a centerfire rifle bullet that could not possibly have been fired from the .22 rimfire AR-7.
The AR-7 survival rifle was developed for civilian sale after its predecessor, the AR-5, was tested and accepted by the United States Air Force but never actually ordered for production and issued to aircraft crews. Hence, an Air Force pilot would never have been issued an AR-7, despite misleading subsequent advertising copy claiming that the rifle was the "choice of the Air Force" (although they didn't actually order any) or "the choice of Air Force pilots" (perhaps when they aren't on duty).
After Rizzolli asks why the sniper fired only one shot, Frost declares that he found a "second shell casing," but he picks up a loaded round (case and bullet) and not a shell casing (the remaining empty case after the bullet is fired). Having been trained in using firearms, a police officer would surely know the difference.
When Korsak concludes that the shooter must have ceased firing because of a stovepipe jam, his reasoning is badly flawed. A stovepipe jam occurs when a shell casing gets stuck in the ejection mechanism and prevents the next round from loading properly. If a damaged shell casing or loaded round was found on the ground, this indicates that the shooter presumably cleared the jam and reloaded the firearm successfully, and therefore must have ceased firing for some other reason.
When Frost, Korsak, and Rizzoli watch the surveillance footage of the 2 white Chevrolets, the cars are 2 different models; the one on the left is a Cobalt, whereas the one on the right is a Sonic.
Dr Isles says that a parakeet died of avian flu but says there's no risk to humans unless they ingest the bird's feces or give it mouth-to-mouth. All forms of flu including avian are respiratory diseases, infecting the lungs. Avian flu is transmitted when drops of bodily fluid from the birds or dust from their feces is inhaled (not ingested) or comes into contact with the eyes.