MacGyver and Laura both peer out of a crack between the shipping container doors. Such a gap is not possible on a sealed shipping container; the only way for a gap like that to be possible is if one of the doors is not secured closed, and would therefore be easy to open.
Near the end, MacGyver blows two wire ropes on one end of the container and it drops and releases boxes of guns on two crims. But with workplace health and safety laws, nobody stands under anything that is being hung from a crane. Also, on containers the sites that connect to the crane are totally on the outside of the container. MacGyver would not have been able to blow the wire ropes.
Breeze tells Maddox "I never even saw the gun until the shooting started". In fact he didn't see any shooting and only briefly saw the gun being held by his friend after his car crash.
MacGyver and other characters are locked inside a container with heavy weapons for transport. This is not a plausible course of action for any credible weapons industry merchant. In particular, this was a candy shop for someone like Mac.