Spurious background fringes have been observed in time-resolved holograms recorded with a pulsed laser source and a rapidly deflected reference beam. These fringes were determined to be a time smear effect due to the small change in the angle of incidence of the reference beam during the exposure time. By analyzing the phenomenon theoretically, equations were derived that could be used to describe the observed fringe formation. A numerical solution was obtained for a realistic laser pulse time profile and an analytical solution was obtained using a simple mathematical model of the pulse profile. These solutions allow an a priori determination of bounds of the exposure parameters that would reduce the time smear effects to acceptable levels.