In "The Patchwork Bear", after the Smurfs and Patchwork Bear crashed their sleigh near a frozen waterfall, Papa Smurf's trousers are white instead of red.
In "Hefty and the Wheelsmurfer," Gargamel opened a wood crate revealing a boa constrictor that he ordered. He says it came from Africa. However, boa constrictors are native to the Americas, not Africa.