The house was built as a standing set in Concord, Massachusetts. It was torn down soon after filming ended.
When Newton first enters his house and finds Gwen there, she is singing "The Name Game". Goldie Hawn uses the names Ollie and Kate, both names of her children in real life.
Meg Ryan was originally set to star as Gwen. When Ryan declined, the producers opted for Kim Basinger. But Basinger also declined, so Goldie Hawn took the part.
In Taiwan it was known as Half a Wife in My Soup. This title reflects Goldie Hawn's first leading movie role, in 1970's M'è caduta una ragazza nel piatto (1970), co-starring Peter Sellers.
When Steve Martin's character meets Goldie Hawn's 'Gwen' who is working as a waitress in a Hungarian restaurant, he goes along in an ironic fashion with her posing as a Hungarian. In actual fact, Goldie Hawn is half Hungarian, on her mother's side.