Goofs

Where Sam is cooling his wrist in the bowl of ice. When he puts it down after Joe tells him to go, its on the sofa. The very next shot it's sitting on the table.

Around 25 minutes in, Joe is seen tinkering with a vacuum tube that no longer has its glass envelope, thus the "vacuum" is gone. This tube will never work again. When powered up, the filament will burn out (the usual failure mode for a vacuum tube) if it hadn't already.

The movie doesn't show the tube being powered up. They do show the plates and grids out of the envelope, but that it how they are made and how it is possible to repair them.

At 24:52, Joe is seen filing the inner parts of a vacuum tube that no longer has its glass envelope, thus the "vacuum" is gone. This tube will never work again. When powered up, the filament will burn out (the usual failure mode for a vacuum tube) if it hadn't already.

The building windows opposite Sam's building don't look closer when the kid looks at with and without binoculars (the only difference is the obvious fake black frame).

During the riot at about 1:25:00, one of the rioter's prop hammers shatters into pieces when he hits the side of a car.

The city was just blacked out, but at the end scene, where Samaritan walks away under the bridge, the lights are on. Also you can see lights far ahead.

The "EMP Grenades" didn't have enough power for long (time) and far (distance).

All through the final fight scenes with Cyrus, Samaritan is shot many times. While he may be bulletproof, his hoodie is not. it should be in shreds from the bullets.

The EMP that Farshad tossed after his fight with Joe detonates with little effect despite it causing massive damage to electrical and electronic devices earlier when one was thrown down a manhole.

Sam's wrist seems to heal as fast as Joe's bones.

There's a limited amount of time movie makers can spend on things unimportant to the plot.

Albert describes to young Sam how the magic hammer was forged, but the flashback depicts Nemesis casting molten metal into a hammer-shaped mold, then hitting the solidified hammer without further changing its shape.

He didn't need to. It is magic. It was forged in the hate Nemesis had for his brother. And flashbacks are notoriously unreliable.

The police officer guarding the armory lacks basic training or reflexes as he doesn't move an inch when "presented with" a detonating device.

That wasn't the armory. It was the evidence locker. The officer behind the counter is basically a clerk, not honed to battle readiness. He did have steady nerves, though.