When Boone talks to Shannon about his and Locke's whereabouts, the symbol on Boone's shirt disappears completely when he kneels beside her.
When Sawyer tells Kate "It's my knee, I'll tell you how bad it is!" his hair is relatively dry and disheveled. In the next shot (showing a wider angle of both characters), it's wetter and hanging almost straight down.
After Sawyer drops the Haliburton out of the tree onto the rocks below, it clearly settles in a different spot from where Kate snatches it up a moment later.
When Shannon takes off her top to sunbathe, she has a bottle of water and a bottle of sun lotion next to her on her right hand side. During the scene with Sayid, the positions of the bottles change repeatedly between shots and in one shot the lotion disappears completely.
The position between shots of the pink blanket wrapped around Shannon changes when she's sitting next to Sayid.
When Kate is swimming under water, at times a nose clip can be seen.
Kate's toy plane retrieved from the Halliburton case changes model in different scenes.
Sawyer's fingers are okay after Sayid pushed the bamboo under his fingernails. They should be blue/black. Wounds like that have to grow out