Animals are never ever silent - dogs whine/bark/yip, cats meow or purr, cows moo, even in cases where most animals wouldn't be making a sound.
In a horror film when there is a full moon there is either an owl or a wolf howling in the distance.
All bicycles have bells (that sounds)
Bombs always have big, blinking, beeping timer displays.
Car tires "always" screech on dirt roads.
Car breaks must always squeak
When in San Francisco, no matter where you are, you always hear a cable car and or a fog horn.
Kids can always whisper even if their two inchs away from a villian - he won't hear. If they step on a branch however, the villians will immediatly know its not some animal, and catch them.
Power Reference
