At 3:14 mins into the opening of this movie, on the computer with a yellow sticky note on a computer monitor it could be seen the words "results from last HIV set, lunch at noon". Ironically this year 2016 , 20 years after this film was released, Charlie Sheen, the lead actor of this film announced he was HIV-positive.
The length of the first signal is 42 seconds. The number 42 is, in The Hitchhiker's Guide to the Galaxy by Douglas Adams, "The Answer to the Ultimate Question of Life, the Universe, and Everything", calculated by an enormous supercomputer over a period of 7.5 million years.
In 1996 this movie and Independence Day(1996) about aliens form other world had had came out in theaters in the same year. 20 years later in 2016 Independence Day: resurgence would come out in theater as well as another alien visitation movie coincidentally called "Arrival" 2016.