During the "Worthless" song scene in the scrapyard, the Surfer car's left (driver's side) headlight falls out soon after being picked up by the magnet. When laying upside-down on the conveyor, the missing headlight has switched to the passenger side.
After Lampy is struck by lightning in order to get power for the appliances' battery, his bulb is broken and the area around the bulb is burnt along with his plug, which disappears after when he obtains a new bulb. The burn marks were actually washed off when the appliances fall into the rapids earlier.
Early on in the movie, Kirby mentions that they have been doing chores and cleaning the Master's house for the last 2000 days, which is nearly five and a half years. However, during the musical cleaning sequence, complex cobwebs are in easily reached areas, the windows are caked with dust to the point of being opaque, and all surfaces seem generally dusty. If no humans have been living there for 5.5 years and the appliances have been "doing chores" as they are shown doing every day, there's no way the house could be as filthy as it is shown to be.
Many times, the various characters demonstrate the need to be plugged in (and actively drawing energy from the power source), while at other times, they seem totally independent (Lampy, for example, can use his light freely, yet it draws down their battery when he is plugged in).