When Kevin first walks by the telephone it has two knots in the cord but when the phone starts to ring the knots are gone.
The opening credits depict Frank's draft notice bearing the seal of the US Army, but this episode establishes that Frank served in the Air Force.
After Frank passes out watching TV, Bill heads to the kitchen to see if his magnet attaches to the toaster. When he does this you can see that the animators forgot to erase where they colored outside the lines on the toaster.