Continuity mistake: When Lagrange finishes dancing with Argylle, she places both hands around his back, the left over the right. A shot later, they're placed the opposite way. (00:02:10)
Revealing mistake: When Elly is "skating" on the black oil while fighting the bad guys, we can see that it is Bryce Dallas Howard's stunt double in a few shots where it briefly shows her face.
Continuity mistake: After they dance, Argylle gives his gun to LaGrange, who bends her arm and points the gun upwards. From the angle shot from behind, her arm is lowered.