Understanding and writing a text arise from several factors. Among them, coreference relations, which allow for the identification of the referents of linguistic expressions, are of particular importance, since they ensure referential cohesion and, thus, contribute to text cohesion. One context in which recognizing referential relations is crucial involves reference chains with anaphoric pronouns. Although all languages exhibit coreference relations, the linguistic means to establish them may vary. Thus, in the context of translation, maintaining reference chains often implies the use of adaptation strategies: when working with non-null subject source languages, such as English, and null subject target languages, such as Portuguese, translators should recognize the contexts in which, in the latter, they may or must omit the subject, without affecting interpretation nor creating vagueness, conflict of interpretations or referential ambiguity. In this work, some data about reference chains in the context of English to Portuguese translation is discussed. We identify the main mismatches in translations done by university students and present clues to help train students in translation, promoting their mastering of the grammatical and textual conditions that determine the omission vs. the realization of the subject. The results show that the main problems result either from calque of the source language properties or from the overgeneralization of null subject contexts in the target language.