When Gramps and Charlie are driving up the driveway, you see Gramps driving from the right side of the car. When he pulls up the house, he's back on the left.
During the battle with the Aztecs, Jess sets the skull on the ground beside him, after which it disappears, until he is seen carrying it as he exits.
Charlie says his Uzi is semi automatic, yet it shoots like a fully automatic. In addition, the Uzi is obviously the semi-auto Carbine model, with a longer barrel that is legal for civilian ownership in the U.S. It is a felony for a civilian to own a full-auto gun without having a federal license for each such gun.
After "Gramps" feeds the worm-dog a bottle of beer, he tells the animal to go off and play, while turning him to the floor. It's then that you can see the obvious arm of the puppeteer, clothed in the same cloth of the blanket "Gramps" is using.
When Bill the electrician first enters the house, the dolly track is clearly visible on the floor for over 30 seconds.
When Grampa turns off the TV, the entire crew is reflected in it.
When Jesse is in the kitchen trying to get the skull from the bird's mouth, you can briefly see the puppeteer operating the bird in the lower right corner of the screen.
When Kate hear the music coming from her friend's room, she exit the study to go see what was that. When she exits a red microphone is clearly visible on the upper right side of the screen.