The barbed wire that Tweety wraps around the pole supporting his nest disappears and reappears between shots.
When Tweety installs the barbed wire on the pole supporting his nest, he is seen nailing it to the post just underneath the nest. In the next scene, when Sam is using the corset trampoline to try to reach Tweety, the barbed wire is seen at the bottom of the pole, but not at the top.