Postgraduate medical training incorporates education, both formal and informal, combined with clinical service. This study explored the early training experience of pediatricians in Ireland and its potential impact on patient safety. We sought to identify factors that contribute to the patient safety experience of new entrant pediatric trainees. Trainees, or senior house officers (SHOs), in their first year of postgraduate training, participated in an interview conducted using a critical interview technique (CIT). They described an adverse event where the medical care delivered to the patient was not ideal. Thematic analysis identified themes that influenced the described event. Thirteen trainees participated in the interviews. This study identified influences on the relationship between the SHO and patient safety, including the SHO themselves, teamwork and communication. Colleagues within the workplace, including consultants, registrars, and nurses, also affect this relationship. The registrar is described as a central figure holding an active role in clinical care in 11 of the 13 stories told. In the participants' experience, the registrar was the senior decision-maker, teacher, team builder, and communication intermediary within the teams' hierarchical structure. The registrars' previous clinical experience, communication style, along with their ability to supervise and provide feedback shaped the SHO experience. Through a process designed to focus on exploring patient safety, it emerged that the registrar plays a crucial role in the working experience of their junior colleagues. The influence of the registrar needs to be recognized within clinical teams and by postgraduate training bodies.