In the years since the show's demise, both Max Wright and Anne Schedeen have stated that tensions were very high among the cast and crew. The technical demands of the series made for very long shooting schedules, and none of the actors enjoyed playing supporting roles to a puppet who always had the best lines.
The final episode ("Consider Me Gone") was, indeed, intended as a cliffhanger. At the time it was filmed, NBC was still up in the air over whether the show would be cancelled. The cliffhanger format was intended to help persuade NBC to give the show one more chance, if only to resolve the "To Be Continued" ending. Six years later, the TV movie Project: ALF (1996) finally brought closure - although the lack of the original human cast, and poor writing, cause many fans to reject Project: ALF as part of the show's canon.
Series creator Paul Fusco told the cast and crew not to give away the secrets to ALF. Fusco operated the puppet most of the time, and provided the voice. However, when full body shots were needed, actor Mihaly 'Michu' Meszaros, who stood only two feet and nine inches tall, wore an ALF costume.
When the show first aired in Germany it became an instant success. But it was unfortunate for the German city of "Alf", located at the Moselle river. The city-limits-signs, featuring the city's name, were stolen so many times, that the city council decided to buy a huge number of signs for sale.
Two kinds of ALF puppets were used: The first one was was remotely controlled and used for all shots where ALF was shown only from the stomach up (most shots). Whenever ALF's entire body incl. his feet were visible(occasionally), another puppet with a human inside it was used. This is easily discernible as the faces of these two puppets look quite different from one another.
ALF (1986) staff writer Jerry Stahl wrote a memoir called "Permanent Midnight" about becoming a success as a television writer on this show (as well as Moonlighting (1985) and Thirtysomething (1987)) while simultaneously dealing with his addiction to heroin. The book was made into the movie Permanent Midnight (1998), starring Ben Stiller as Stahl, and showed several scenes on the set of "ALF" (renamed "Mr. Chompers"), including a nightmarish drug-induced hallucination featuring the show's puppet.
Unfortunately, only the edited (by 3-5 minutes per episode), syndicated versions of the ALF episodes are available as Region 1 DVDs. The German DVDs (Region 2) feature the full episodes as originally broadcast; they also include the English audio.
The Alf puppet was operated from various "trap doors" hidden within the set. This made filming the show somewhat more hazardous than a normal sitcom as the cast had to remember where each of doors were so that they could avoid them.
Max Wright was so ready to be done with the show that on the final day of taping, once it was over, he immediately cleaned out his dressing room and left the studio without saying goodbye to any of the cast or crew.
In 1987 and 1988, Topps issued a series of trading cards based on the show. And in packs of the cards, randomly inserted were Bouillabaisseball cards. Bouillabaisseball was a popular sport on ALF's home planet. It was like Baseball, only a rotting fish was thrown instead of a ball. The cards depicted some of the great and not so great players of the fictional game.
Irish national broadcaster RTÉ were forced to cancel an episode of ALF on 25 June 1990 as the FIFA World Cup game between Republic of Ireland and Romania went into extra time and penalties. Although Ireland won and the nation celebrated the historic achievement, some viewers complained that the episode was not shown.
At the time, was one of the most expensive 30 minute sitcoms to produce due to all the technical elements required and long taping schedules. To help recoup costs, NBC licensed the character to other things such as toys, breakfast cereal and an animated TV series.
Due to the technical difficulties of taping the program and to not give away the secrets of ALF, the show was taped on a closed studio set with no audience. An audience laugh track was used to make it sound like it was recorded in front of a live audience.
The writers for the show tried to push the envelope on what type of jokes and scenarios they could get away with on the program. However, NBC pushed back on them and insisted on more "family friendly" scripts when they realized that ALF was attracting many younger viewers.