Before he is slapped in the Prologue segment, Billy (Joe Hill) already has red slap marks painted on his face.
When Hank enters the graveyard to look for Aunt Bedilia, the hanging lantern (which Bedilia had previously hit her hat on) has now gone.
The direction the 'Popov' vodka bottle faces changes between shots in the second segment of the film, "The Lonesome Death of Jordy Verrill".
During the segment "Something To Tide You Over," the hole that Wentworth is buried in shakes unrealistically when he yells for Richard to stop.
In "Something to Tide You Over", when Richard goes to the beach after the couple has drowned, he picks up a bucket. He takes it out of the wet sand, yet he empties obvious dry sand from it.
During "The Crate", when Wilma is making a fool of herself at the luncheon, she says the line "Whoever that etiquette crotch is." Not only does the line barely match the movement of her lips, the line is said in a voice that doesn't quite match Adrienne Barbeau's. Internet research reveals the original line was "Whoever that etiquette c**t is," but was changed in post-production at the request of Warner Bros.
Near the end of the "Father's Day" story, Sylvia gets impatient and goes to the kitchen calling to Mrs. Danvers. She sees the muddy footprints and investigates further. Mrs. Danvers' corpse falls against the back of the kitchen door with her face in the round window. As Sylvia lets go of the door, you can see the dead Mrs. Danvers blink as she slides across the window out of view.
In the segment "The Crate", when Henry "shoots" Billie, the hole in her forehead appears one frame AFTER the blood spray comes from the back of her head.
As Richard hurriedly drives his Jeep away from Harry's buried head, the back window is swung up. With the tide quickly coming in, he must hurry. As Richard approaches his house, the window is down. On this model of Jeep, the spare tire must be swung away from the window in order to close it.
Sand on Harry's faces disappears and reappears between shots as Richard buries him.
In the segment "Father's Day" - which purportedly takes place on Father's Day (which is in June) - it is already completely dark outside by 7pm. By this time in June it wouldn't be completely dark outside until much later in the evening.
In "They're Creeping Up On You," Upson Pratt smashes a cockroach with the butt of his gloved fist (in a close-up), and in the next shot his white glove is clean as he looks at it. If he is imagining the roaches, as the movie implies, the glove would be clean.
The Lonesome Death of Jordy Verrill - The impact zone around the meteorite would have been oblong since the trajectory of the meteor was at an angle. The perfectly round shape featured implies an impact perpendicular to the earth.