When Patrick Jane comes to Shirali Arlov's house to talk about the painting, he is instructed by the guard to use the intercom to state his presence. In an up-close shot of the intercom, numbers "31416" are seen on the display, as some form of a status code. Given numbers are a clear reference to the mathematical constant PI, rounded up to 4 decimals (PI = 3.1415926535...).
Red-haired actress: Darby Standfield.
The plot is very similar to the Michael Caine/Shirley MacLaine movie "Gambit" (1966).
The painting hanging to the left of the stolen one in A. P. Caid's office is Rembrandt's Christ in the Storm on The Galilee Sea. The original was famously stolen from the Isabella Stuart Gardener in 1990 and the inclusion of the painting in this scene is thus a nod to the theme of art theft. However, it also makes head of security's statement "Only one thing is missing, but it is the most valuable painting he owns" (spoken while the viewer looks at The Storm hanging in the office) somewhat nonsensical: The painting missing from the office ('The Moro') is repeatedly stated to be worth 50.000.000 USD. and the Rembrandt is estimated to be worth twice that.