Homeward Bound II: Lost in San Francisco (1996)

Plot hole: The house fire first started when the dog catcher threw the cigarette in the dry grass next to the house. When Shadow and Sassy find out the house is on fire when they're passing by, the exact side the fire started at isn't burning. How did the fire even get inside the house?

Sassy: Does the cat always have to be the brains of the operation? Beauty and brains. I never cease to amaze myself.