While writer Kevin Lehane was backpacking across the world and being bit by mosquitoes, he heard the urban legend that eating Marmite (a vitamin B rich yeast spread) prevents mosquito bites. Hearing that, he wondered whether mosquitoes also got hungover from drunk people's blood. The thought stayed with him until he returned home and wrote the script for Grabbers based on the premise 'get drunk to survive'.
Before shooting, director Jon Wright took actors Richard Coyle and Ruth Bradley out drinking and filmed them while drunk. Ruth Bradley discovered many quirks about herself while drunk that she used in her performance.
The film's shot during the harshest winter in Ireland in over a hundred years. Uncharacteristic blizzards, gale force storms and sub-zero temperatures regularly hampered production, creating a difficult shoot.
The Grabber in this movie shares many characteristics of the Facehugger from the well-known Alien, el octavo pasajero (1979) franchise starring Sigourney Weaver. The movie contains many allusions to the Alien 2: El regreso (1986) series, including recreating the famous scene where Sigourney Weaver takes on the Alien Queen in a futuristic forklift with the famous line "Get away from her you b**ch!"
Near the beginning of the film, there is a welcome sign for Errin Island. This features a cartoon sun exactly the same as the one on the holiday sign for Amity Island in Tiburón (1975).