Continuity mistake: At the shopping mall when Sully does the cash exchange (in the envelope) he picks up the money and puts in his pocket, then in the open shot it's back on the table.
Revealing mistake: When Matrix reaches Arius' mansion (in actuality the Harold Lloyd Estate), he is rushed at by several soldiers of Arius' private army and starts shooting at them with his RPK. In one shot from Matrix's rear we can see him shooting four soldiers at the same time. However, the two soldiers on the far left drop dead even though Matrix is aiming his weapon to the right. (01:11:40)
Continuity mistake: During the machine gun scene at the en Matrix has a belt fed M60 machine gun. When the fight starts, he has plenty of bullets. A few seconds later he has about 20 cm length of the bullet belt left. Scene switch - and he has more bullets. This switch between low and high ammo a few times. (01:16:15)