Goofs

(at around 1h 27 mins) After they escape from the Terminator on the plane Grace is holding a cup in her right hand but in the next shot her hand is on the wall and the cup has vanished.

(at around 9 mins) In one scene Diego is seen putting on his shirt. In the next scene he has managed to put a t-shirt under the shirt.

(at around 2 mins) The very first scene after the flashback on the beach as the water coming in reveals the skulls. Each successive "wave" uncovers the two skulls in the frame. As the camera pans down away to more skulls the "waves" apparently stop washing in.

The wake of the boat that passed had moved on along the shore. No wake, no waves.

(at around 1h 13 mins) When Dani, Grace and Sarah are sitting on the porch discussing tactics with Carl, the beer bottle in Dani's hand moves between the table and her hand in between shots.

(at around 27 mins) The 'Toyota' on the truck is 'subdued' when Grace drives off, but is 'bright when she arrives at the pharmacy.

(at around 58 mins) The movie shows both men and women put in the same cages at the detention center. In the United States, adults are always separated by gender.

(at around 1h 3 mins) During the riot in the US immigration detention center Sarah Connor, who is being escorted out of the facility by local police but still in the main holding area manages to get a hold of a gun from one of the police officers sent to transfer her. No firearms are allowed in a main holding area so they would have not had a gun on them.

(at around 6 mins) Several patrol cars at Mexico City have the words 'Policía Municipal' written on them, which means municipal police. However, Mexico City has no municipalities, and contrary to a patrol car from any other state in the country, no official vehicles are labeled as 'municipal'.

Arnold Schwarzenegger's terminator is credited as and referred in the Trivia section as a T800. But when 'Carl' first introduces himself to Dani and Grace, he refers to himself as a Cyberdyne Systems T101.

The terminator model number CSM-101 is the unit number within Cyberdyne Systems. You can even see this number in the sunglasses of the original terminator in posters from the movie that started it all. T-800 is what humans call this model. Very similar to how the model F-117 is known as the stealth fighter.

(at around 1h 13 mins) In one scene, the T-800 is seen with a dog cuddling up next to him. In the first two Terminator films it is established that dogs bark incessantly and become agitated when a Terminator is present, hence the reason why they are used to help humans in detecting them.

However, in this movie the scene is used to suggest that the T-800 has changed and is no longer the same machine it once was. In addition, if the dog was raised around a terminator there is no reason it would not be used to being around one.

(at around 3 mins) It has been suggested that in the second film, which was set in 1995, John Connor appeared to be a teenager who was, based on his appearance and voice in some scenes, just entering puberty, and since in the opening scene of this film is set in 1998, John hasn't aged/grown nearly as much as he should have in that time.

However, in Terminator 2: Judgment Day (1991), while Edward Furlong who played him was 14, the actual character of John Connor was only 10, and as the opening scene of this film is set three years later means that John would only be 13.

The processor in T-800 Terminators is set to 'read only' when they are sent out alone so are unable to learn unless the switch is manually reset, however, the T-800 in Dark Fate states that it learned from humanity to integrate into it which it should not have been able to do.

All T-800s are aware of the 'read and write' mode in their CPU. After completing his mission Carl had no purpose so it could have got it manually switched from 'read only' whenever it wanted to. Or he could have already been in 'read and write' mode the whole time. Additionally, the idea that the Terminator's CPU is set to "read only" is solely from the extended cut of Terminator 2: Judgment Day (1991). In the theatrical cut, the Terminator is implied to be automatically set to "read and write."

Grace has incredible strength, speed, and agility, and is able to go one on one with the REV-9 advanced terminator, yet there are several scenes where Grace visibly struggles to restrain Dani, a slight human female, much smaller than her.

This is likely because Grace does not want to injure Dani.

(at around 1h 2 mins) When Sarah and Agent Rigby are in the stairwell fighting, her hands are supposed to be cuffed behind her back. When he pins her to the wall, she uses a free hand to push herself away from the wall. Also, they attached one cuff to each wrist with no chain the middle.

The Toyota Land Cruiser the protagonists drive is missing headrests in the front two seats.

(at around 1h 26 mins) A C-5 has a takeoff speed of 150-175 miles per hour. It also ascends at a steep angle. You cannot stand on the ramp as shown in the film while it's taking off or in-flight.

Grace knew the back door was open, so she didn't ascend at a steep angle in case anybody fell out.

(at around 1h 13 mins) Carl is supposed to be "400 lbs" yet he is sitting on a deck chair that seems to hold the weight without any kind of straining or warping.

Many standard deck chairs could hold 400 lb, but his were made from square tubular steel, so - no problem.

(at around 1h 30 mins) Hitting a plane with another airplane will nearly always cause both to come apart in mid-air. The C-5 would have been falling in pieces , not remaining intact.

Not in this case. The C-5 was fortified with a thick layer of plot. It did come apart eventually.

The REV-9 shows up to pursue the lead characters near Laredo wearing an El Paso PD uniform and flying an El Paso PD helicopter. El Paso is almost 600 miles away from Laredo.

So what? There's no reason El Paso PD wouldn't have an urgent special interest in a border jumper and send somebody to pick them up.

They didn't use the helicopter to go the 94 miles from Carl's place to the military base. Instead, they drove the van.

They wanted to avoid the attention that flying a stolen copter near the military base would generate. Also, arriving for an illicit secret meeting with Major Dean, who is committing treason, is best done unobtrusively.

(at around 21 mins) There's a 2006 Audi Q7 driving around in Mexico; the first Q7s sold in North America were 2007 models.

The early setting of the film is supposed to be Mexico City which is in a large temperate mountainous valley. It's clear from the surroundings in the film that they are in a desert plain which would actually be hundreds of miles north of Mexico City.

And Madrid, Spain, standing in for Mexico City, is actually ~5600 miles north of Mexico City. It's not an error. The film makers knew where they were. Creative geography.

When the lead characters get apprehended by the USBP near Laredo, an El Paso PD car is present. El Paso is more than 600 miles away from Laredo by car.

The T-800/Carl's home is located in a heavily forested area in Laredo, Texas. Laredo's located in a dry grassy plains area consisting of grass, mesquite and cacti with no large forests.

(at around 19 mins) A Volkswagen Golf hit by the REV-9's truck has a European-spec license plate frame.

(at around 18 mins) A BMW sedan in Mexico during the pickup truck chase is seen having a European-spec license plate frame.

This is proposed to be a direct sequel to the events of Judgement Day, yet the prologue in that film is that Sarah lives to be at least in her sixties while John becomes a senator and that is how he helps to prevent the rise of Skynet. Him being a senator in 2029 and then being killed in 1998 is not in direct sequence.

While in the auto plant the rev 9 uses the nano bots to build a gun which he throws away essentially a part of itself,

One of the Rev-9's greatest tactical advantages is its ability to split into two independent units. Yet, when Grace intervenes at Dani's workplace to protect her, it fails to use this ability, even though doing so would have allowed it to engage Grace while simultaneously pursuing Dani, ensuring a more efficient attack. A tactically unsound choice for a machine designed for optimal efficiency.