Continuity mistake: When the grocery boy walks up the porch to knock on Mrs. Hooper's door, the sun is shining on the backside of the house. When it cuts the sun is suddenly shining on the front of the house, hitting the door. (00:02:35)
Visible crew/equipment: After Roger has a Vietnam flashback while he's at his computer, the movie playing on the TV catches his eye, and he watches for a moment, then when he clicks it off we can see the reflection of equipment and crew on the dark blank TV screen. (00:25:55)
Visible crew/equipment: When Roger hears Jimmy's laughter he follows the sound upstairs. Then, while Roger is in his late aunt's bedroom he grabs hold of the closet doorknob but decides not to open it, and as he leaves the bedroom the moving boom pole casts a shadow on the wall beside the closet door. (00:27:40)
Continuity mistake: When Cobb notice the toy car rolling over the floor, the car stops on the right side of the black square on the floor. When it cuts the car is on the left side of the square. Also the sunlight on the floor differ between the shots. (00:39:50)
Visible crew/equipment: After the gardening tools attack Roger in the shed, when Roger loads the shotgun to confront the marlin mounted on the wall, just as he enters the room and stops, the boom operator's raised arm is visible on the left side of the screen. (00:43:45)
Revealing mistake: While Roger is in the bathroom he hears banging, and when he opens the door he sees the gardening tools poised to attack, and in the shot from the bedroom facing Roger, we can see the stunt wires attached to the hedge shears as it hovers in front of the door's wood casing. (00:44:35)
Visible crew/equipment: After Roger shoots the Witch, when Harold goes to his window he sees Roger's shotgun and calls the police. In the next shot, as Roger kneels beside the body, we can see the black screen equipment on the porch, on the left side of the screen. (00:46:05)
Visible crew/equipment: After the dog digs up the Witch's hand, when Roger repeatedly shouts, "Stay!" the dog bolts, and as the canine runs out of the yard, we see there's someone standing behind the tall bush as the dog turns toward this person. Then, when Roger fails to catch the dog, as he tries to open the car doors, the reflection of a crew member is visible on the car's rear window. (00:58:40)
Continuity mistake: When Roger is about to make an escape through the bathroom window, we can see the blinds are pulled all the way up. When it cuts the blinds are pulled half way down. (01:14:45)
Continuity mistake: When Roger is lowering himself down the hatch inside the mirror, a flying demon grabs his shotgun. At first the demon grabs the shotgun at its barrel, in front of Roger's hand. When it cuts the demon's hand is on the handle behind Roger's hand. (01:15:05)
Continuity mistake: When Roger is running away from Ben, Ben breaks through the window and walks through it. Two shots later the window is suddenly mended. (01:18:55)
Continuity mistake: While Roger is trying to get away from Skeleton Big Ben he's wearing his army boots, but when Roger is walking on the roof of the house, the footwear of the stunt double looks nothing like Roger's army boots. (01:23:20)
Continuity mistake: When Roger babysits Robert, the neighbour's son, he begins to cry, so Roger sits with him and watches TV. All of a sudden the tears on the childs face miraculously dry up between cuts.
Continuity mistake: When Roger returns from leaving his partner Ben who is captured by the Vietnam enemy, note the position in which Harold is holding the stoker object in his right hand whilst propped on the mattress, it moves from his stomach to his upper chest between cuts.
Revealing mistake: Later into the film Roger realises that his aunt's paintings hold some significance to the whereabouts of his missing son. He removes a cloth from the top left of a painting revealing an image of his son trapped in his bathroom cabinet. Note the cabinet door is the wrong way round to the one in his bathroom.
Continuity mistake: When the Sandy/demon tries the blow Rogers brains out he opens the bathroom door containing the 'floating garden tools'. The hedge cutter shoots towards Sandy/demon lopping off her head. Next scene Roger picks up the head placing it in a bin bag, but there's no blood, but there was when he shotgunned a hole in her from an earlier scene.
Visible crew/equipment: In the Sandy/demon scene, when the cops arrive an officer says, 'I know you, right? You're Roger...' you can see the boom mic reflected on the visor of his police cap.
Continuity mistake: The Sandy/demon scene. When the cops arrive an officer says they had a report of 'someone at this address firing a shotgun'. But Harold who made the call to the police regarding his neighbour reported a 'suicide' attempt.
Continuity mistake: The Sandy/demon scene. When Roger escorts the cops to the front door, he says 'My gun' and we see the cupboard door under the stairs (containing Sandy's body) is ajar. But when he closes the front door behind the cops the next shot shows the cupboard now closed.
Continuity mistake: In the Sandy/demon scene she knocks over the big round wooden table that has an ornament on. After Roger shoots her he picks up the table but does not replace the ornament. Yet when the cops enter his house the ornament is back on the table.
Answer: That's the horror movie Don't Look in the Basement (1973), at its own timecode 01:09:30 within that movie.
Super Grover