The low prevalence effect (LPE), a decrease in target detection performance as target prevalence decreases, is a concern in real-world visual search tasks, such as baggage screening. Unfortunately, much of the research into the LPE and its potential countermeasures may not represent the challenges of other real-world search tasks, such as sonar and security monitoring, in which objects in the search environment exhibit movement. Additionally, target (e.g., submarine) and non-target (e.g., merchant ship) movement may interact with target prevalence to further decrease target detection performance, but these factors have not been systematically manipulated to determine their effects. In Experiment 1, high and low prevalence targets occurred in search conditions with static or randomly-moving objects. Although there was no significant interaction effect detected between target prevalence and motion, these conditions independently contributed to significantly lower hit rates. In Experiment 2, a higher prevalence target was included as an attempted LPE countermeasure. Observers searched for a relatively high and a low prevalence target in the moving search task. The addition of a higher prevalence target improved target detection overall in a search environment with moving objects, serving as a possible countermeasure to the LPE.