Visible crew/equipment: During the long car chase, after Freya tells Matt that he's an awful driver Matt makes a sharp right turn and the car chasing them stops short, and when they back the car up we can see the reflection of a crew member wearing a hat (perhaps the cameraman) on the car window.
Revealing mistake: While Contini's train speeds along the railroad tracks, in the train's cab when Contini opens the floor's trap door before Freya walks in and later when Matt pushes Contini through the open trap door, there are closeups of the ground below and there are no railroad tracks whatsoever.
Continuity mistake: During the long car chase and later when Yu-Rang and the other baddies are in the cars chasing after Matt and Freya, their cars' rear-view mirrors keep vanishing and reappearing, between closeups and wide shots. Additionally, during some closeups of Matt and Freya the car's windshield is gone to provide a better view of them.
Revealing mistake: When Matt and Freya are attacking the compound, at one point he goes outside and throws a "hanky panky" grenade at what looks like a garage door. He throws himself over a hedge and a moment later the grenade explodes. When he is getting up, the "ground" is obviously a cushion covered with fake grass.