In the restaurant, Gargamel throws a plate with bread up in the air with Azrael, it falls and a breaking sound is heard. However, seconds later, the plate and the bread are on the same place as if untouched.
Papa Smurf and the other 5 Smurfs travel around New York by riding on top of the Taxi. It's daytime. By the time they got to Patrick's apartment, it's night.
When Patrick Winslow encounters his boss as he's coming in on the first day of work after his promotion, she comments that he seems to have "nervous energy". He gestures awkwardly in the air with both arms and replies, "nervous energy's what's going on up in here!" Halfway through his reply the camera angle changes and he's no longer lifting both arms; he's gesturing with only his right arm, while his left arm is clutching a folder to his chest.
Just after the Smurfs arrive in Central Park and the portal closes, the round tube used to create the physical water pinwheel effect is visible behind the waterfall.
When Gargamel approaches the 'Wizard' there is a shot of Gargamel's rear head shot, revealing the wig not fitting as there are two bulges.
When Patrick is using Google to search for information on smurfs, the icon on the bottom-right shows his laptop is charging the battery. Before and after this scene however, it is clear the laptop is not connected to anything, so it is certainly not connected to a power source.
In some scenes in the streets of New York, a crowd watching the recordings can clearly be seen at the end of the street.
When Clumsy runs to the waterfall, Grouchy says that they are down to 99 smurfs, implying that there are 100 smurfs in total. In fact, counting smurfs introduced after the events of The Hundredth Smurf, there are 105 smurfs.
When Odile asks Gargamel what it is that he desires, she asks "Riches? Fame? Fortune?" In terms of wealth, riches and fortune mean the same thing.