'She wrapped up her damn cat'

Possibly. Sometimes cats are very docile and will just sit wherever you put em'. The cat probably just laid down and went to sleep, but then woke up or got more active when all the noises from the Griswold's and the smell of the dog hit it.

But the cat looked pretty old and tame/quiet when it was chewing on the Christmas lights strand.

just saw on the morning news the xray of cat in Suitcase at airport security check in, lady claimed to be unaware the cat was packed

cats like to be inside boxes

What happened to the cat in this movie was messed up. Then again Chevy Chase wanted to cheat on his wife with that woman from the perfume store.

I'm amazed the poor thing didn't suffocate. That box had no holes in it. But then again, the stupid thing died less than an hour later after being unwrapped, eating all the smaller lights on the tree, and getting electrocuted, so....