The plot of this episode is slightly reminiscent of the case of Stella Nickell who was sentenced to 90 years in prison for product tampering in May of 1988. Mrs. Nickell allegedly poisoned at least 2 bottles of Excedrin capsules with cyanide. One was given to her husband and the other replaced on the shelf of a store which resulted in the death of Susan Snow. Because of the seemingly random nature of the poisonings, it was first believed to be a contamination of the manufacturer. After this was ruled out, the police began to focus on the significant others of the deceased.
When Marie is at the optometrist for the second visit, the doctor jokingly says, "Please tell me this is Marie's twin sister." In real life, the character of Marie is played by twins.
When Allison asked Joe for alternate names for a parking garage, he said he thinks it's called a car park in England. Jake Weber, the actor who plays Joe Dubois, was born in London England.