At the beginning, Mac is making a disaster in the kitchen, notably a big pot of something boiling over. In most of the shots, it has a major head on it and is boiled completely over. In one shot, the contents are still within the pot when Mac is wiping the side. In the next, it's back to being boiled over.
After the grenade breaks the toothpick, releasing the ''spoon" the grenade explodes immediately. Unless the grenade was defective it would have at least a 3 second delay.