Early in the movie we clearly see Mr. Waikiki shot by small arms fire. He later tells the nurse he was shot by a 45mm weapon. What he should have said was that he was shot by a .45 caliber weapon. 45 millimeters is about 1.75 inches and is certainly not small arms fire and does not match the bullet holes we see inflicted upon him.
Nice states that she had shot herself to get into Artemis in order to get close enough to her target, the Wolf King.
Except Wolf King was said to be arriving because the bank robbers had mistakenly taken the pen with Wolf King's diamonds from a customer after a change of plans, not knowing what was inside, and they only were going to Artemis because they were wounded in an unplanned shootout. Nice had checked into the Hotel before any of those coincidental actions had taken place.
After Honolulu died when his life support was cut off there is the standoff when Waikiki gets a hold of Acapulco. He shoves his head into a 3D printer and turns it on to kill him. Except the whole reason Honolulu died was the power to the entire building was cut off, so the printer would not have been operational.
Both Waikiki and Acapulco were able to create guns inside the weapons-free facility using parts made on a 3D printer. However they would not have been able to get the bullets to use the guns, though they are shown to fire them later.