The big killer is the Easter lily. I have to mention this even though it is not Easter because this was not discovered until recently. If your cat chews on this, it will most likely be fatal. Lots of things may be laying about that could cause obstructions if eaten. Styrofoam, ribbons, the strings and nets used to wrap meats, plastic wraps, ornaments, tinsel, and small toys, to name a few.
Electrical cords seem to sprout in wild profusion with all the lights and decorations.
Be sure that they are inaccessible to pets that are prone to chewing. Antifreeze is deadly and, unfortunately, tastes great to pets. Even very small amounts are usually fatal. Clean up spills at once. Keep containers tightly closed and properly stored out of reach of children and pets.