Factual error: In the scene where the young Helen Goff is traveling by train with her family, it's obvious that an American engine and coaches have been used, instead of a Queensland Rail locomotive of the era. None of the QR locomotives had flared smokestacks like on the one seen in the movie. The coaches are also incorrect - as far as I know, none of the Queensland Rail wood coaches had clerestory roofs with a set of windows in them like seen in the movie. When Helen looks out the back of the train, it's also obvious that the tracks are spaced at 'standard gauge' (4' 8.5"). They should be closer together, as railways in Queensland are built to 3'6" gauge instead. There is also no such company as the 'Queensland Victoria Railway Co', as marked on the coaches, as all railways in Australia are state owned.
Factual error: In the scene where Kevin is floating, eating a banana just before he is converted in a monster, the water begins to spin in a clockwise direction, but Kevin spins in the opposite direction. He should spin in the same direction as the water. (01:02:45)
Factual error: Dewey corners the gang in the wrecked Mystery Machine and pulls out his duster, which a blade pops out of. There is no way that blade could have fit in the duster. The blade is much thicker than the handle of the duster, and it is longer than the handle and the feathers combined. (01:04:55)