(at around 13 mins) Betsy Russell, who portrays Sergeant Hamill, was a featured character in the Saw (2004) film franchise. When the character Neil first receives the chain letter, the original "Saw" is playing on his television in the background.
In addition to Betsy Russell, seven other stars of the film have starred in other notable horror movies/franchises. Michael J. Pagan, in See No Evil (2006); Charles Fleischer, in Les Griffes de la nuit (1984); Keith David, in The Thing (1982); Matt Cohen, in Boogeyman 2 (2007); Michael Bailey Smith, in L'Enfant du cauchemar (1989) and the remake La colline a des yeux (2006) and its sequel La colline a des yeux 2 (2007) albeit as different characters; Noah Segan, in Cabin Fever 2 (2009).; and Brad Dourif as Chucky in Jeu d'enfant (1988).