Wilson says that he wrote the book 'The Psychophysiological Indices of Amorous Connections Among Termites of the Southwest'. In 'Wilson's Girlfriend', that book was supposedly written by Jill's psychology professor.
Wilson's entire face is accidentally shown for a brief moment at the end, right before the Beach Boys sing Barbara Ann.
When the Beach Boys are at the back fence singing "Barbara Ann" with Wilson, their mouths do not match the soundtrack.