The influence of sight can overpower aural senses when locating a source. However, mismatches between the position of a sound source visually and aurally causes cognitive dissonance (it's unsettling), which can hurt the audience's emmersiveness. For professionals, just a 4 degree mismatch on a horizontal plane between the visual and aural positioning is noticeable, whereas for the average layman it takes 15 degrees.
Something moving left to right across and then off the screen will seem to continue "into the exit sign". Even though the sound system doesn't technically have the ability to accomplish this, our vision overwhelms our aural senses and suggests it.
