Throw It In: Most of David Lee Roth's speaking breaks, combined with Crowning Moment of Funny. "Eruption" also started initially as a warmup before Templeman convinced Eddie to record it and put it on the album. The rain in the background of "Could This Be Magic?" is actual - the band opened the studio's door during a rainy day because it was hot and poorly ventilated, and the effect got caught on tape.
By the way, the person saying "c'mon, Dave... gimme a break!" in "Unchained" is Templeman himself, telling Dave to stop before his talking got out of hand.