When Percy, Valentina and Anton are counting money and Valentina says: "Hey, maybe my birthday won't be so bad". Percy is looking down at money in his hands. In the next shot his posture and facial expression is completely different.
When Dr. Parnassus is following Valentina through the concourse two young school girls in uniform pass him. Moments later when he's outside looking in the window, the same two girls can be seen entering the library.
At the part where Tony (played by Colin Farrell) and Valentina are in the Gondola, there is a shadow of someone walking behind the screen, in the back, between when they are talking about how perfect it is and that they have to make a choice.