Memories are readily distorted. What conditions allow memories to be altered? Converging evidence implicates prediction error, or surprise, as a key mechanism that renders memories malleable. Recent reconsolidation studies have used incomplete reminders to elicit prediction error; retrieval cues that partially replicate an encoding experience allow memories to be distorted, updated, and strengthened. Here, we review diverse evidence that incomplete reminders govern human memory updating, ranging from classical conditioning to naturalistic episodes. Through the unifying theme of predictive coding, we discuss evidence from reconsolidation theory and nonmonotonic plasticity. We argue that both animal and human reconsolidation research can benefit from critically examining prediction error and incomplete reminders. These findings bear implications for pathological fear memories, false memories, misinformation, and education.