FAQ for
Close Encounters of the Third Kind (1977) More at IMDbPro »

No, it was only a sleeping gas - the same agent used to knock out the livestock and caged birds.

There are three official cuts of this movie:

1) The Theatrical Version is the original version that was released in theatres in 1977. Its runtime is 135 minutes.

2.)The Special Edition was released in 1980. Director Steven Spielberg was rushed to meet the release date of the film in 1977 and he felt that this compromised his vision of the film, particularly with regards to the special effects. Columbia Pictures then offered him the chance to fix the problems he saw with the original release and also gave him a budget to film additional scenes as well as improve the special effects. Included in these are a scene in which an old naval vessel (the SS Cotopaxi) is found in the desert, and, most notably, an extended ending in which we follow Roy into the mothership. In turn, this version of the film also deletes some scenes (such as where Roy is throwing the dirt and garden objects through his kitchen window, and the earlier scenes of Roy at work), though the introduction to his family is longer, and there is a new scene where Roy is having a nervous breakdown in the bathroom. Its runtime is 132 minutes.

A detailed comparison between the Theatrical Version and the Special Edition with pictures can be found here.

3) The Director's Cut was released on home video in 1998, and is Spielberg's favored version. In this he uses footage from both of the previous versions, such as Roy's breakdown in the bathroom as well as the scene in which he is shovelling dirt into his kitchen window. Also restored is a press conference scene which was removed from the Special Edition. The scene of the SS Cotopaxi in the Gobi desert (from the Special Edition) is still included, however, Spielberg opted to remove the extended ending inside the mothership as he felt that including it was a mistake (he stated that the inside of the ship should have been left to the imagination of the audience). Its runtime is 137 minutes.

A detailed comparison between the Theatrical Version and the Director's Cut with pictures can be found here.

A detailed comparison between the Special Edition and the Director's Cut with pictures can be found here.