This slip up is in the movie at the part where Pistachio and Jennifer are going to the toy fair. Pistachio is disguised as "Gammy Num-Num" and it is when Devlin Bowman comes up and says that the Nest In A Box is of 12th century Tuscan.

If you watch when Devlin Bowman is talking to Jennifer, Gammy Num-Num keeps popping herself between the two. Watch how Devlin Bowman pushes Gammy Num-Num away. It's about the second or third time he does it. At one shot he is pushing her away by reaching across his body with his right hand. In the next shot while he is still pushing her away, he is pushing her away with his left hand.