When Phyllis Diller walks into the witness room looking for Denny Crane, she says that the met briefly during World War II. Denny later says to Alan that they were "frisky in a foxhole". Denny's age has been established to be 72 as of Season 2, so Denny would have been at most 11 years when this friskiness was to have happened while Phyllis Diller, who was born in 1917, would have been in her late 20's. It could, however, have been a deliberate mistake made by the writers for some reason.