Other mistake: When one of the bad guys looks through the mail box slot, Alex sprays him in the eyes with black spray paint. Meaning the spray paint must have actually gone INTO his eyes, yet when he turns around, its only around the outer part of his eyes and nowhere in his eye balls.
Other mistake: When Alex's mum calls the woman thief at the scene where the thieves are redirecting the phone calls, the screen shows Alex's mum dialling a number. The call is redirected to the thief's mobile, but notice that on the computer screen, "Interrupt" is spelled wrong, and instead is spelled "Interupt".
Other mistake: When Jernigan says, "Gotcha" when Alex comes into the room and Jernigan falls, it shows him falling but his expression doesn't seem like he is actually scared.
Answer: It appears to be a mixed breed of dog.