Goofs

When Riggs and Lorna are driving together in a car right before the bad guys try to push them in front of the train you can clearly see that the car has a digital speedometer. When they are being pushed onto the train tracks the speedometer has changed to analog.

The series, "Lethal Weapon" is named after Riggs who, as established in the first film, is an expert in martial arts. Despite this, in this film Riggs appears to have no martial arts ability; behaving more like a boxer.

During the massive fight scene, Roger's gun fires 7-9 shots, and his pistol is supposedly a six-shot Smith & Wesson revolver.

The scratches on Leo's face come and go in the final scenes.

Murtagh and Riggs floor the gas pedal during the scene when the car crashes through the building, but another shot shows that the brake lights at the rear of the vehicle are on.

In the tail credits, there is a film crew photo. The photo purports to be the crew of "Lethal Weapon 4", but is actually crew photo of "Fortress" with Christopher Lambert. Photo taken December 1991.

When Riggs pulls the restaurant's fire alarm pull station handle, the sprinklers also spray water. The sprinklers would only go on if their fusible links melt due to heat (from a fire).

In the scene from the prison in China, as the Chinese men are being loaded onto a Boeing 727, the pilot inputs LAX (Los Angeles Int'l Airport) as the destination from Peking (Beijing), China. This would be impossible to fly on a Boeing 727 without stopping to refuel several times, as the 727 has a maximum range of roughly 3,000 miles - not enough to fly non-stop from Beijing to L.A., which is roughly 6,300 miles apart.

Also, in the scene showing the prisoners boarding the 727, we see a shot of the cockpit. In the center above the computer display, the engine gauges are visible in four columns. This would indicate that the aircraft has four engines, however, a 727 only has three engines.

Although Murtaugh impales Wah Sing Ku with the metal rod, and it went completely through his body, he was still able to fight Riggs under the water. This would have done irreparable damage to his internal organs, and caused internal bleeding. He would more than likely have lost consciousness from blood loss quite quickly.

When Riggs is trapped underwater by a slab of concrete, Murtaugh strips off his coat and dives head first into the water. A trained policeman or emergency worker would always jump feet first, because of possible hazardous debris not visible from above. While some might see this as a goof, the fact is that police are not routinely trained in water rescues.

At approx. 50:19, when Riggs is holding on to the roof of the building in Chinatown, Mel Gibson's Australian accent is clearly heard when he sarcastically yells, "could you have found something smaller". Gibson spent a great deal of his youth in Australia, hence the accent. Some might consider this to be a goof, but at no place in the franchise does it say where Martin Riggs spent his youth. All that is known is that he was in the military in the sixties, went to Vietnam, and that he served in the military police (the latter via a certificate on the wall of his trailer).

The Murtaughs' family vehicle, parked in the driveway of the home, has the exact same license plate number as the big black Mercedes driven by the bad guys Riggs and Murtaugh chase on the freeway.

In the beginning of the movie when the gas tanker flies into the air, one shot clearly shows the edge of the artificial rainstorm.

After Riggs and Murtaugh have stopped "the human torch" and are walking off in the rain, Murtaugh is wearing only his boxers, due to the rain, it can be seen through his boxers that he's wearing black briefs underneath.

When the Chinese captain is running up the chairs in Chinatown and Riggs follows him, you can clearly see that it's not Riggs but a stunt man.

During the car chase, Riggs and Murtaugh keep passing by the same landmarks multiple times, revealing that despite the length and speed of the chase, it was all done with multiple takes across the same small mile or so stretch of road. The Home Depot/Walmart sign is passed by at least five times, and the Luxor and Mandalay Bay resorts (actually Las Vegas landmarks, see also Errors in Geography) out in the distance never seem to get any closer despite the cars being driven down a road that would take them that way.

As Riggs is fighting on the back of the truck, the undercarriage of the helicopter being used for aerial footage is briefly visible.

During the shoot out between the boats, a pan from the freighter to the "Code 7" shows a lighting array obviously not on either vessel.

When the Chinese truck is rammed by the second train, two cameras are clearly visible on the ground to the right of the train: black cloth-wrapped boxes with circular glass faces, mounted at 45-degree angles toward the vehicle, with stage lights behind them.

After the scene where Lorna tells Riggs who the father of Murtaugh's grand baby is, when Riggs and Lorna pull up to Murtaugh's house and Riggs opens his door to get out of the truck, reflected in the door are several crewmen standing around in front of Murtaugh's house.

When Riggs drives up to his trailer home for the first time, the chrome plated front fender of his pick-up clearly reflects the feet of the steady-cam operator walking along the front of the car, plus a small tripod possibly used for a reflector.

The scene where Riggs is dragged on a table down a highway was supposedly set just outside Los Angeles, yet the Luxor Hotel and Casino in Las Vegas is clearly visible in the background.

The car chase (and most of the movie for that matter) is supposed to take place in and around Los Angeles, but much of the car chase was clearly filmed in Las Vegas on the 215 freeway. Some of the major giveaways include the Luxor and Mandalay Bay Hotel/Casino resorts visible in the distance in some shots, a freeway exit sign in the style of Nevada, not California, said exit sign being for Eastern Avenue, which is a major Las Vegas street, Black Mountain being in the background in several shots, and a sign for the Eastern Beltway Center visible in several shots (it's got signage for Home Depot and Wal-Mart stores). When Riggs gets back in the car with Murtaugh, the scenery goes back to Los Angeles, although there's still at least one Las Vegas/215 insert shot after that.

During the highway chase, just after Riggs falls out of the mobile home and is riding on the overturned table dragged by the tarp, Murtaugh calls for help and says "This is William Three Fifty-Six in pursuit." The proper LAPD call sign should be "Three William Fifty-Six" (Division/Station Number, Unit Type, Unit Number) While Murtaugh could've gotten flustered giving the call sign, he's a long time veteran of the LAPD and is trained to give proper information over the air no matter how excited he is.

Detective Ng and Uncle Benny pronounce the Chinese currency starting with a Y sound but in standard pinyin its spelled Renminbi therefore pronouncing the currency would begin with an R.