Twice during the film Ecks is knocked flat and props himself up by pressing the barrel of his gun into the ground. Not just poor weapons handling, any debris in the barrel could cause the gun to malfunction.
When Ecks is in the police bus picking the handcuffs, he is holding the paperclip with his right hand and picking the cuff on his left wrist. Suddenly, the cuff comes open around his right wrist, but the paper clip is still sticking out of the left cuff's lock.
After the motorcycle chase, Ecks is laying on the ground and Sever places Eck's pistol beside him close to his head. The gun is clearly not cocked. The next time we see the gun, moments later, it is cocked.
In the covered garage, before Ecks encounters Sever, he manually loads a shotgun round into the already open breech, then moves the slide into place, racking the new round. It is obviously ready to shoot. When he does encounter Sever, we hear the sound of the shotgun slide being racked as though there had been no round in the chamber.