Thomas and Johnston retired in 1978 , and both later enjoyed cameo appearances in the Brad Bird-directed films The Iron Giant ( Warner Bros. , 1999 ) and The Incredibles ( Pixar , 2004 ) . Thomas , Johnston and Davis retired in 1978 , and Thomas and Johnston later enjoyed cameos in the Brad Bird-directed films The Iron Giant ( Warner Bros. , 1999 ) and The Incredibles ( Pixar , 2004 ) .