Continuity mistake: In the carnivorous plant scene, Manny grabs the fruit (the bait), which is sitting in the middle of the plant. In the next few shots, the bait disappears and then is replaced with a bulb that housed the red and blue "wires".
In the beginning, Scrat is sniffing for his acorn and reaches the end of the cliff. Before he reaches the end, look at his saber teeth closely; they've disappeared. When his nose goes over the edge, they reappear.