Versace purchases several magazines at the news stand at approximately 7 minutes but seconds later as he walks back to his home the magazines are gone.
When Andrew Cunanan is being chased through an alleyway after assassinating Gianni Versace, an electric cart/taxi is seen at the end of the alley. Those electric vehicles did not exist at the time.
By 1990 the Medusa logo, which origins Versace explains to Andrew after the opera hadn't yet been introduced. It was launched in 1993.
Young Andrew and Young Gianni were seen writing/drawing with their left hands. The adult actors were both right-handed. Gianni Versace was right-handed in real life.