The hobo's truck is seen passing a white signpost as it pulls away after picking up Jaime and Max, yet after the long interval of Jaime's thoughtful pondering and the truck's driving away and Jaime's dictated letter heard in voiceover, the truck is seen rolling away into the distance on the same short section of road, and it finishes passing the same signpost, even though over a minute has elapsed.
Jaime rolls up the window of her car to keep Max inside but leaves an inch-wide space at the top for air. Yet when Max is playing peekaboo with the little girl, the window is all the way up.
The dart Rudy loads in the tranquilizer gun was different than the one shot at Max.
When Jaime first brings the enormous dog-dish over to Max's cage, the bowl is heaped high almost to overflowing, and the meat is pink and fresh. Yet in the subsequent shot of Jaime trying to coax Max to eat it, there is much less food in the dish, and the hollowed-out portion of the meat is brownish in tint from having been exposed to the air for a while. Obviously, this difference is because the dog actually did eat some of the meat, and so now the reason that he is ignoring the dish is merely that he is totally stuffed (the humongous bowl holds so much food that normally even a big dog like Max could never have eaten all of it), not that he dislikes the choice of meal or that he was not hungry to begin with.
When Jaime first meets her young mother friend and toddler, the VW's passenger door is closed, then in the scenes where the child is waving the flowers at Max, the door is open, and then after the girl kicks the gearshift and the car starts to roll, the door is closed again.
The tubular rear bumper that Max is grasping visibly turns back and forth as the dog pulls on it, clearly showing that the tube is just a fake bumper that is not even rigidly fastened to the car.
When Max grabs the car's rear bumper in his teeth, additional tooth-marks are already visible on the bumper, indicating that this shot was a later clip from a series of takes, and that the dog had previously grasped the bumper several times during previous takes.
The white sides of the hobo's truck as it drives away - and the whole surrounding scenery with its rich colors and strong shadows, in fact - is much too brightly lit to have been filmed at night, with just moonlight to illuminate the scene; also, the sky is dark blue, not black with stars. Obviously just an underexposed daylight shot to look like nighttime.
The shadows of roadside trees pass across Jaime's face to indicate that the truck has started to move, yet the sound of the transmission being engaged had just sounded an instant earlier, and the revving engine sound is heard a moment later (but again, this is heard AFTER the shadows pass across Jaime's face), so the truck supposedly had been stationary until then, and thus the tree-shadows should have been stationary, also.
It is stated that Max was trapped by a lab-fire as a puppy, yet the "flashback" scenes clearly show Max as a young adult dog, with a long snout and lean-bodied figure. German Shephard puppies are much more snub-nosed and roly-poly than adults.
Sheriff John is not heard from till Part 2; he is the Chief at the distant location where Jaime ends up in her quest for old-flame Roger. So the officer in the roving Ojai patrol car would not have been talking with Sheriff John on the radio, since presumably the local officers would only speak with each other and their in-town Chief on their radios, and nobody would have known to what area Jaime had gone yet.