John Cusack was the first choice for the role of Alex Wyler, but he declined.
Sandra Bullock revealed in an Entertainment Weekly interview that the title house had running water but no toilets.
The name of the exclusive restaurant in the film is "Il Mare". "Il Mare" is also the name of the house and the International title of the Korean film upon which "The Lake House" is based, Siworae (2000).
The construction site that Reeves' character is working on is real. It is owned by Pulte Homes and is the Madison Park Community in Aurora, Illinois.
First movie to be released simultaneously on DVD, HDDVD and Blu-ray Disc.
Sandra Bullock states that she felt compelled to name the dog "Jack" after the character of Keanu Reeves in Speed (1994/I) - the first movie the two of them made together.
The address of the building in Chicago at which Sandra Bullock lives is 1620 Racine. This would place it in the same block as the apartment belonging to Sean Connery in The Untouchables (1987) (Connery's character lived at 1634 Racine).
Director Cameo: [Alejandro Agresti] man using breath spray on the bus, beside Sandra Bullock.
The lake house measured 2000 square feet and sat on top of steel beams ten feet above the waterline. It used 35 tons of steel and required nearly 100 carpenters, welders and painters to build it.
Simon Wyler's death date is listed as October 6, 2004. October 6 is also the birthday of Swiss architect Le Corbusier, one of the two architects mentioned as his influences when he designed the Lake House (the other is Frank Lloyd Wright).
The actual house did not exist and was built for the movie, then dismantled. The coordinates are 41° 42' 49.92" N, 87° 53' 10.56" W. (Google Earth can be used to view this location now, and using the History feature, the house can still be viewed.)
The Lake House used was located on Maple Lake, a small and well known haunted fishing lake located in Willow Springs, IL.