Onions contain a compound which is toxic to the red blood cells of cats. The red blood cells are destroyed and this results in anemia. The specific type of anemia is called 'Heinz body anemia' because the red cells develop an abnormality called a 'Heinz body' which can be seen under the microscope.
Dug, the dog, is easily distracted by ... squirrels (well, he's easily distracted by everything, but especially squirrels). He can be talking (yeah, it's Pixar/Disney so the dog talks) & right in the middle of the sentence, he shouts, Squirrel!. Then he carries on with whatever he's talking about.
At the beginning of Toy Story 2, Slinky is the one who finds Woody's hat, and joins Buzz, Hamm, Mr. Potato Head and Rex on a mission to rescue Woody from Al McWhiggin. His springy coil is used as a bungee cord when the toys jump from the roof of Andy's house.