Edit
Paranormal Activity 3 (2011) Poster

Goofs

Anachronisms 

Dennis gave Kristi and Katie some M&Ms the night they slept outside in the tent. One of the girls ate a blue M&M. This movie was set in 1988, but blue M&Ms weren't introduced until 1995.
The Barbie doll that can be spotted on the lower part of the screen during the rotating camera sequences throughout the movie is an early 2000s model, making it impossible for it to have stood in a 1988 home as depicted in the movie.
6 of 6 found this interesting Interesting? | Share this
Share this: Facebook  |  Twitter  |  Permalink
Throughout the film, Kristi carries around a stuffed killer whale. This is actually a stuffed version of Willy from the Free Willy series which was not produced until 1993. It is apparent due to the three black spots on the underside of the stuffed whale's chin. Paranormal Activity 3 is set in 1988 which would make it impossible for this toy to have existed.
4 of 5 found this interesting Interesting? | Share this
Share this: Facebook  |  Twitter  |  Permalink
In the film Julie talks about Virgin Mary on a slice of toast, this famously happened in the late 1990's.
5 of 7 found this interesting Interesting? | Share this
Share this: Facebook  |  Twitter  |  Permalink
While Dennis is editing one of the video tapes, there's one on a table labeled "89" even though the film takes place in 1988.
2 of 5 found this interesting Interesting? | Share this
Share this: Facebook  |  Twitter  |  Permalink
While Katie's family are driving to Grandma's house, Dennis turns the camera around and from the back-view of the car, two contemporary cars are seen parked in the background as the family drives past them; because the whole cars can't be made out, the "curved" tops are noticeable.
Is this interesting? Interesting? | Share this
Share this: Facebook  |  Twitter  |  Permalink

Audio/visual unsynchronised 

When Dennis is talking to Kristi after watching the first night's tape, she says, "He's my friend," but it doesn't match the movement of her lips.
1 of 4 found this interesting Interesting? | Share this
Share this: Facebook  |  Twitter  |  Permalink

Boom mic visible 

Its shadow can be seen on Randy's back as Dennis follows him (with the camera) to the garage, after the Bloody Mary scene.
0 of 1 found this interesting Interesting? | Share this
Share this: Facebook  |  Twitter  |  Permalink

Continuity 

The vase of flowers on the dining table downstairs disappears and reappears randomly throughout the movie.
1 of 1 found this interesting Interesting? | Share this
Share this: Facebook  |  Twitter  |  Permalink
In the Director's Cut on Night #7, when Dennis goes to get the camera after hearing noises, the time on the camcorder says it's near 3:43am. Albeit in the next shot when he has the camera, the time still says 3:42am (this was probably an error by the editor).
1 of 1 found this interesting Interesting? | Share this
Share this: Facebook  |  Twitter  |  Permalink
At one point, the family is in front of the house to take a picture of Kristi on her first day of school. This is the photo that was burned in Paranormal Activity 2 and found in Paranormal Activity. In those first two films the girl in the picture is said to be Katie, not Kristi.
1 of 2 found this interesting Interesting? | Share this
Share this: Facebook  |  Twitter  |  Permalink

Miscellaneous 

While driving the Mercedes to the house of grandma, the gauges on the dashboard clearly show speed is zero and the engine is cold.
8 of 8 found this interesting Interesting? | Share this
Share this: Facebook  |  Twitter  |  Permalink
The 1980s video equipment room has a road case for modern electronic equipment. One is a CDJ (Compact Disc Jockey) road case. Portable professional CDJ equipment did not exist until the mid-to-late 90s.
3 of 3 found this interesting Interesting? | Share this
Share this: Facebook  |  Twitter  |  Permalink

Incorrectly regarded as goofs 

While the film takes place in 1988, the home video tapes are presented in wide screen and high-definition quality. However, this is a necessary and deliberate change on the part of the crew, and not an error. Producing a movie with "authentic" quality based on the equipment that existed back then would make a horrible quality for it to be seen in theaters and the movie would be unusable to most theaters.

Plot holes 

In the first PA, Katie mentions about how that the "ghost" was in front of her bed, although we never see it in any of the nights.
1 of 2 found this interesting Interesting? | Share this
Share this: Facebook  |  Twitter  |  Permalink

Revealing mistakes 

When Julie gets off the phone with her mother to answer the door, the camera begins panning back to the dining room. Just before Julie gets back into view, the dining room chairs' positions, table shadow and the beige couch's change. This is indication that the "Kitchen Drop" scene was performed later on in the day; then CGI stitched together to pull off the illusion that an impossible feat was completed in seconds.
1 of 2 found this interesting Interesting? | Share this
Share this: Facebook  |  Twitter  |  Permalink
In one scene, where Dennis receives a couple books from Randy (who's also operating the camera); the beginning of the shot shows Randy filming his reflection on one of the TV's; but it's clearly another person filming the shot, the guy's shirt is white and his face doesn't belong to that of Randy.
Is this interesting? Interesting? | Share this
Share this: Facebook  |  Twitter  |  Permalink

Spoilers

The goof items below may give away important plot points.

Anachronisms 

In the second trailer during the house fire scene, modern suburbans can be seen in the background; clearly the ones made in the 2000s, not consistent with the film's setting of 1988.
0 of 1 found this interesting Interesting? | Share this
Share this: Facebook  |  Twitter  |  Permalink

Continuity 

In the final scene, Dennis is violently back; a lamp is knocked to the ground. The lamp shade (which is on the ground) briefly changes position during a cutaway, when Kristi walks past the camera as her dress briefly conceals the view.
1 of 2 found this interesting Interesting? | Share this
Share this: Facebook  |  Twitter  |  Permalink
In the second trailer when Kristi can be seen inside of the family's car, the camcorder's time tag shows it reading "PM" rather than "AM", since the scene depicting in the trailer takes place at night.
0 of 2 found this interesting Interesting? | Share this
Share this: Facebook  |  Twitter  |  Permalink

Plot holes 

It is strongly implied in the first two films a house fire occurs back in Katie and Kris ti's childhood; albeit it never happens in this film. (The scene was shot but was cut out, although you can see the parents' bed on fire in the end during the static)
Is this interesting? Interesting? | Share this
Share this: Facebook  |  Twitter  |  Permalink

See also

Trivia | Crazy Credits | Quotes | Alternate Versions | Connections | Soundtracks

Contribute to This Page