Matthias Hues, who played the film's alien bad guy, performed all of his own stunts because there were no doubles who could match his size (Hues is 6-foot-5).
A rewrite of the script was penned by writer/director David Koepp.
Prior, director Craig R. Baxley had another project that dealt with an alien called "Man to Man" that was to be produced by Joel Silver, but it got canceled a a few days before filming. Dolph Lundgren had also been rumored to be attached.
The "alien gun" is a modified Calico M950
The project was initially titled "Lethal Contact" (as it was first written in 1984 as a spec script by Jonathan Tydor). The production, filming and international title is "Dark Angel", and was released as such worldwide, before it was changed to "I Come in Peace" for the late U.S. release, because of two other existing movies entitled "The Dark Angel" (from 1925 and 1935).
The shopping center where Caine pursues a stolen Houston Police squad car commandeered by the villain is the former Park Shops Shopping Mall originally built in 1985 in the east end of Downtown Houston. The Park Shops was renamed Houston Center in late 2003 right after the Toyota Center and Hilton Americas Hotel was completed, along with the expansion of the George R. Brown Convention Center.