Enzo G. Castellari was asked to direct this film early in its development, but turned it down on the basis that he was not a fan of horror and primarily made action films. However, he suggested his friend Lucio Fulci as a possible replacement.
While shooting on location in New York City, Captain Haggerty, who plays the large bald zombie who attacks the harbor patrol at the beginning of the film, walked into CBGB's (a tiny Bowery bar which was a flourishing punk rock venue at the time) in full zombie makeup complete with splattered fake blood and mud caked all over his face and body. Due to the outrageous punk styles in those days of the other bar patrons, he was barely noticed. Even the bartender never looked twice at him.
Despite being called "Zombi 2", the film is not a sequel to anything. When Dawn of the Dead (1978) was released under the title "Zombi" in Italy, this film was retitled "Zombi 2" to cash in on the success of the American film. This was done by the studio without Director Lucio Fulci's permission or knowledge, and he often told fans this wasn't a sequel, and that it is it's own film. He was relieved to find out the film's actual title "Zombie" was kept in the American release.
Hordes of the living dead stumble across the Brooklyn Bridge at the end of the film. Although a national state of emergency had been declared and the local radio station had been overrun by zombies, the traffic below still flows freely. This was due to budgetary constraints - there was not enough money to stop traffic on the bridge.
When the final scene of the zombies walking across the Brooklyn Bridge was filmed, it was cold drizzling rain that day and the extras playing the zombies had to keep themselves from shivering. Also, the fake blood had some ammonia in it to stop it from changing color. When it dripped into the actors mouths, they would spit it out when the cameras stopped rolling. All of the extras playing zombies in the New York scenes were paid $40 per day in two $20 banknotes which had a single staple through them so as not to overpay anyone. The director Lucio Fulci, spoke very little English, his only direction for the zombie extras had was "like... ah... this!"
The film was written before Dawn of the Dead (1978) was released in Italy, as an action/adventure thriller with no link to George A. Romero's films. The opening and closing scenes (which take place in New York) were added to the script later when the producers wanted to cash-in on the success of Dawn.
The make-up effects were done by renowned Italian Giannetto De Rossi. The make-up for the zombies was "caked" on in several stages and Lucio Fulci, the director, constantly referred to the extras as "walking flower pots".
Like many Italian horror films of the time, half the cast spoke only English and the other half only Italian. Many Italian films produced for international distribution filmed without sound and recorded several dialog tracks in different languages in the studio for later overdubbing. Because the actors are speaking a number of different languages (or some are speaking a non-native language phonetically), the dubbing in all versions of the film is not 100% synchronized. Ian McCulloch, Tisa Farrow, Olga Karlatos, and Stefania D'Amario were of the main English speaking cast, while Al Cliver, Auretta Gay, and Dakar were of the main Italian-speaking cast.
When first submitted to the BBFC in 1980, the movie was passed with an X rating with 1 minute, 46 seconds cut. Then, with the Video Recordings Act, it was banned in 1984 as a "video nasty". It was removed from the DPP list, and the original cinema release was re-rated in 1992 with an 18 rating. In 1999, it was once again re-rated, with only 23 seconds of cuts for an 18 rating. Finally, it was passed uncut with an 18 rating in 2005, with a 91 minute run time.
Although 'Zombi 2' was made to cash-in on 'Zombi''s (Dawn of the Dead) success, script writer Dardano Sacchetti based his script to 'Zombi' on 'I Walked with a Zombie', 'Voodoo Island' and 'The Walking Dead', stating that he wanted to bring the zombie genre back to its Caribbean and Voodoo roots.
Scriptwriter Dardano Sacchetti chose to take his name off the credits due to his father's death during preproduction. As a result of his loss, Sacchetti felt uncomfortable about being connected with a movie about the dead returning to a semblance of life and then being destroyed.
The zombies in this film were modeled to resemble the original voodoo legends of the walking dead from Hatian and Caribbean legends of people after being supposedly reanimated from being dead. In contrast to the zombies in George A. Romero's 'Dawn of the Dead' and other zombie films, nearly all of these zombies walk with their heads down, their eyes closed, and with their arms always at their sides. Only three zombies featured have their eyes open.
Since there was no cgi at the time, and the production didn't have the budget for fancy animatronics, a real tiger shark was used for the infamous zombie vs shark fight scene. The tiger shark is one of the most dangerous shark species that exists, so the shark's trainer, Ramón Bravo, fed the shark right before filming as well as doping the shark up with sedatives. Bravo also stepped in to play the underwater zombie after the original actor fell ill.