Goofs

The slow-motion scene in which Riggs falls from the highway is filmed from two angles. From above, one can clearly see that he's falling towards a padded mat. From below, he falls through a pile of boards.

After Jack shoots Billy in the interrogation room, there is a big blood spot on the wall behind Billy. When Riggs, Murtaugh and Cole come in a minute later, the blood spot is gone. Additionally, Jack shoots Billy in the middle of his chest but when Billy slumps, there's no blood on the back of the chair.

When Riggs is demonstrating the cop-killer bullets on the firing range he shoots at a bullet proof vest several yards away. As the vest is being bought back to Riggs you can see the bullet hole where the bullet went through the front and back of the vest. This means it penetrated two layers of armor. At the construction site Lorna wears two vests. Travis shoots her from only a few feet away yet the bullet only penetrates one layer of armor, not two.

When Riggs is following the villains' pickup truck, they turn into a highway and a plane is spotted landing. It is a Lockheed L-1011 Tristar from Delta Airlines. In the next shot, apparently on the same spot, the plane suddenly changes to an Airbus A300 from American Airlines.

During the armored van chase, the same blue station wagon is passed at least twice.

Near the end of the armored car chase scene, Riggs causes one of the bad guys to fly through the armored car's front wind shield. These would normally be made of bullet resistant glass several times thicker than regular glass which would have stopped a human body without even cracking.

The motorcycle Riggs has commandeered apparently knows about its own imminent demise. As it plummets to the ground, its siren changes pitch and dies out before it actually hits the ground.

At the hockey game when Riggs gets the idea to use the public address system, they are announcing a penalty on the Los Angeles Kings. Moments later when the Kings score, there are five L.A. skaters on the ice, but only four Toronto players meaning the penalty was actually on Toronto, not Los Angeles.

In an underground station under construction (or refurbishment), the running rails would not be live, so there would be no chance of electrocution.

In the final shootout scene when Riggs checks Lorna's vest(s), you can clearly see entire rounds of ammunition protruding from her vest, including shell casings (primers visible) - there should only be projectiles.

During the shootout at the burger stand, Murtaugh's gun switches from a silver automatic to a black revolver. However, after Murtaugh empties his automatic he can be seen reaching for his secondary weapon, the black revolver. It's common for police officers, especially plainclothes officers, to carry a back-up weapon.

Riggs is sporting a pony tail when he is demoted to patrolman, doubtful that any police force would allow a uniformed officer to have long hair let alone a pony tail.

Many police departments have protocols in place for officers with long hair, usually women. With Riggs's demotion being so sudden, not giving him time to cut his hair, if such restrictions on male officers exist, clearly he has been given some leeway in this regard with the provision that he put his hair in a ponytail.

Roger incorrectly tells his son to shave "with the grain." This is because Roger is used to an old-fashioned so-called safety razor, which is not as forgiving as a modern razor and can dig in when shaving against the grain.

Shaving "with the grain" or "against the grain" is ultimately a personal preference, even with modern razors, so Roger wouldn't be "incorrect" in his advice.

After Riggs writes on the form, and puts all of those medical procedures on the form, no one seems to recognize the fact that the handwriting is Riggs and not the doctors, this should be easily noticed by any trained medical staff, as they deal with the doctor everyday. This makes no sense and this should have canceled any medical procedures and the doctor could have possibly lost his job.

Medical staff do not deal with the same doctor every single day, in a hospital setting there are various shifts for both nurses and doctors, and anyone who has ever had to read a doctor's "chicken-scratch" will know that recognizing the doctor's handwriting is not realistic.

Riggs and Murtaugh are busted down to patrol after being blamed for the bomb going off, however, the bomb was on a timer and would have exploded anyway in the short amount of time it had left on the countdown.

Riggs and Murtaugh are not punished simply because the bomb went off, but because they went against protocol by not waiting for the bomb squad to arrive and deal with the matter. By doing so, they made things worse because the bomb went off sooner than it otherwise would have giving everyone less time to prepare.

The security guard at the hockey rink is replaced by a dummy as he is roughed up.

The scene after Travis shoots Leo on the ice, and Riggs chases after him, when Riggs loses Travis in the maintenance corridor and starts kicking and cursing for losing him. Look closely, you can see the set painting drawn to look like the corridor continues much further out (look at the ceiling, you can clearly see the end of the set painting).

The motorcycle cop Riggs commandeers the bike from is already handing him the spare clips as he asks for them.

As Murtaugh turns from the motorcycle wreck, the last several frames of the shot show the cable supporting the motorcycle.

As the villains attempt to flee, they and Riggs drive onto a section of freeway that is being newly constructed. However, there are already skid marks on the road surface. These appear to be from previous takes on the scene as they match the truck's path perfectly.

The lumber in the housing development is dark and has obviously been exposed to the elements for two years; which corresponds to the actual time that the sight - a genuine, failed development - had been abandoned. New lumber would have been far lighter in color.

When Riggs jumps onto the front window of the Subway and flashes the driver his badge, the driver shouts out "Police!", but when you look at his reflection off the window, his lips don't move.

When Travis is telling Captain Murphy why he loves the police station in Murphy's car, Travis's reflection in the rear-view mirror shows that his lips are not moving.

Steadicam and operator visible when Riggs' motorcycle falls from the highway.

After Rigs grabs the parking ticket off his truck's window, the camera tracks over to Murtaugh in the passenger seat. As the trucks pulls away we can see the camera matte box with "Panavision" clearly visible as a reflection in the window.

During the armored vehicle chase scene, right before Riggs unlocks door and enters cab, a crew member is seen strapped on to the roof of the armored car.

(At minute mark 25:23) The reflection of the car-mounted camera is visible in the scene in which Riggs and Murtaugh discuss Murtaugh's retirement.

When Riggs and Murtaugh start firing during the final shootout, camera equipment is reflected on the pile of wood they are hiding behind.

After Lorna gets shot, Riggs is checking her pulse with his thumb on her throat. Anyone who's ever had first aid training knows this is a big mistake because the pulse you will feel is the one running through your own thumb. Pulse checking should always be done without the thumb.

During the final shootout, Jack Travis does not get involved until the guy wearing glasses runs to his office and tells him it's the cops they're burning everything. Over the previous few minutes, there were lots of gun shots and fires being lit, while Travis just stayed in his office doing nothing.