When the kids are interrogating Sparks they ask him what his weakness is and one of the twins says "Water? Earth germs?". These are references to two well-known alien related films; in Signs (2002), the alien's weakness is water and in La guerra dei mondi (2005), their weakness is the common cold.
Working title: They Came From Upstairs. This title appeared in some early promotional materials before being changed to Alieni in soffitta (2009).
At 17:10, Sparks, the first alien Tom and Jake encounter while on top of the roof, tells them "Hello, humans. We come from upstairs." This line was probably intended as a joke, where the word "upstairs" is mistakenly used to mean "space". It is also the likely source of the working title "They Came From Upstairs".
Ashley Tisdale and Austin Butler are distant cousins in real life.