According to the production notes, there were bizarre incidents on set of life imitating art. On the seventh day, the production office was discovered to have flooded overnight, the result of a burst water pipe. Water is a strong theme in the film. In response, Director Hideo Nakata requested a Japanese purification ceremony be carried out by a Shinto minister, but the strange incidents continued. While on-location, a swarm of bees descended on the prop truck, prompting the immediate evacuation of the department, before the bees left as quickly as they had arrived. For no apparent reason, a five-gallon water jug burst open in the production office kitchen, once again flooding the same room that had flooded earlier. One morning on the Universal lot, a Set Decorator stepped out of the parking garage to discover an antlered buck charging across the asphalt in her direction. Though deer are a regular occurrence in the hills, the similarity to the deer attack in the film is uncanny.
When Rachel takes the pills and puts them on the sandwich for Aidan, she crushes the pills into a powder. The medicine bottle has a label that can be seen with the name Tony Bonaventura, who is the Property Master for the film.
When Naomi Watts and her son go to the outdoor Astoria Antique Fair Swap Meet, Watts picks through a bunch of used VHS tapes at a vendor's stand - and all the movies are DreamWorks titles, such as Old School (2003), and Win a Date with Tad Hamilton! (2004).