Recent experiments have demonstrated that error-related negativity (ERN) is not only elicited when people commit errors, but also when they observe others committing errors. The present study investigates whether this observed ERN is also present when participants observe execution errors in an everyday context. Participants observed short sequences of pictures showing steps of everyday actions ending either erroneously or correctly. Participants were instructed to indicate by a delayed response whether the observed action was correctly executed or not. The results showed a large P300 for execution errors compared with the observation of correct sequences, but no ERN activity was found. The present experiment indicates that the detection of execution errors in observation does not rely on the error processing mechanism responsible for generating the ERN. The increased P300 amplitudes suggest a more general monitoring process that signals that the occurrence of unexpected events is involved in the detection of execution errors.