Introduction: There is reliance on radiology registrar reporting of after-hours CT scans in many public hospitals across Australia and New Zealand. This study evaluates the extent and nature of CT reporting discrepancies after-hours by comparing trainee preliminary reports with consultant finalised reports. Methods: A retrospective review of all after-hours CT scans between January and December 2014 by radiology trainees at a level 1 trauma centre was performed. Discrepancies were classified as major or minor, by year level of trainee, time of report and scan type (Trauma vs. Non-Trauma). Major discrepancies were investigated to assess if they led to increased morbidity, mortality or a change in treatment. Results: 17,948 after-hours CT scans were performed. A total of 1235 preliminary reports required addendums (discrepancy rate of 6.9%). There were 630 Trauma and 605 Non-Trauma studies. There were 56 major (0.3%) and 1179 minor (6.6%) discrepancies. Of the 56 major discrepancies there were 12 (0.3%) in the Trauma and 44 (6.6%) in the Non-Trauma groups. There were no adverse patient outcomes due to any major discrepancy. There were more minor discrepancies in reports of Trauma CTs compared to Non-Trauma (P ≤ 0.0001). No relationship between the time of report issued and discrepancy rate (P = 0.811) was observed. There was a lower discrepancy rate the more experienced the registrar from year 2 to advanced fellowship (P = 0.003). Conclusion: The discrepancy rates of after-hours CT trainee reports were lower at this institution compared to international literature (6.9% vs. 7.7%). The majority of preliminary trainee reports were accurate with no increased morbidity or mortality resulting from major discrepancies.