This paper first gives an insight into the problem of evaluating translations and lists existing approaches. After introducing error taxonomies, a comparative error analysis of Google Translate results is conducted based on the selected taxonomy. The analysis covers translations from English and German into Croatian, and from Croatian into English and German. The intra and inter-annotator agreements, which are rarely accounted for, are reported where applicable. The aim of the paper is better understanding of different notions of error analysis and detecting weak points of such analysis. A preliminary list of guidelines for error analysis is suggested.