Continuity mistake: At the beginning of the film, we see boots walking through the woods. In a closeup they stop, and to the left boot there's a cluster of leafless branches. In the following shot from behind, they are gone. (00:00:50)
Visible crew/equipment: When Tommy is at Jason's grave, a white reflector screen is clearly reflected into his glasses. (00:01:15)
Continuity mistake: When Tommy is at Jason's grave, the stones around Jason's grave are different from the closeup to the aerial shot. (00:01:20)
Continuity mistake: When young Tommy is looking at Jason's grave the amount of leaves on the grave change between the shots. (00:01:20)
Continuity mistake: Jason stabs the machete vertically into the man's stomach, but when he pulls it out the machete is in horizontally. (00:03:30)
Revealing mistake: When Jason is raising the machete above Tommy in the woods, it's obvious that his eyeholes are covered with black cloth. This also happens at the end of the movie, where Tommy hallucinates about Jason in the hospital. (00:04:45)
Revealing mistake: After the "Friday the 13th" logo explodes, the supports that were holding up the model are briefly visible through the smoke. (00:05:40)
Continuity mistake: When Tommy is dropped off at Pinehurst, the way he holds his bag changes between shots as he walks through the door with Pam. (00:09:15)
Continuity mistake: In the film Tommy tosses the alien mask that he wore to scare Reggie on his bed and the mask slides down the wall and is all crinkled up. In the following shots Tommy takes out another mask and you can see the alien mask now laying flat on his bed and away from the wall. (00:13:10)
Audio problem: When everyone is running after the police car, we hear Robin shout "Hey guys! Joey, c'mon!" but her mouth is shut. (00:14:05)
Continuity mistake: When Ethel says "Now, I wanna tell all of you. Mark my words." she has her arms down. When it cuts she leans her left arm against her waist. (00:15:55)
Continuity mistake: When Ethel and Junior take off on the bike, the shades surrounding the police car differ between shots. (00:16:25)
Continuity mistake: When Joey walks out onto the porch, he has a yellow chocolate bar sticking out of his sweater. In a following closeup it has gone but it reappears in the next wide shot. (00:17:20)
Visible crew/equipment: As Joey walks over to Robin and Violet, who are hanging up washing, a large set of lights is reflected in the window as he walks over. (00:17:45)
Continuity mistake: In the film Joey has chocolate on his face/left side of his mouth. The amount of chocolate changes on his left side as he is walking off the porch towards Violet. (00:18:00)
Continuity mistake: When Robin and Violet hang up the laundry, the distance between the pink towel and boxer shorts increases between shots. (00:18:15)
Factual error: When Vic is in the police car, there should be a screen separating the front from back seats. (00:20:35)
Visible crew/equipment: In the film the ambulance is called to Pinehurst. When the ambulance comes to a stop the boom mike can be seen in the bottom part of the rear window. (00:21:05)
Visible crew/equipment: As Pete walks off into the woods, the cameraman's shadow is briefly visible on his back. (00:23:50)
Revealing mistake: When Vinnie has a road flare shoved into his mouth, it is obviously a dummy as the road flare is inserted (his skin is much paler than in previous shots). (00:24:30)
Answer: Several possibilities: 1 The mother requested he not make any contact, 2 They could've moved away, and he lost contact until then, 3 He may have been drafted into the army, and she could've divorced him during his time away and moved into whatever state this is located.
Rob245