The pandemic represented a context where rapid changes to planning, organization and service delivery were undertaken to respond to an urgent and life-threatening health system problem. There was intense interest in knowledge mobilization--mechanisms that allow the timely sharing of evidence with the aim of supporting improvement--to mitigate the pandemic's threat to public health and service delivery. In previous literature, one suggested vehicle for rapid knowledge sharing and health service innovation during the pandemic was communities of practice. The concept is that these informal networks sparked knowledge sharing in response to a novel problem; they were later joined by institutional or formal networks that were aligned with the communities of practice model. While sympathetic to this communitarian reading of the response to COVID-19, it jars with my personal experiences of rapid knowledge mobilization during the pandemic (including an experience of plagiarism of COVID-19 related research which stimulated this intervention), and it neglects more critical thinking on the topic of communities of practice. The experience of plagiarism is presented as an introductory vignette, a discursive method used in the communities of practice literature to enable links to be drawn between specific empirical cases and broader conceptual themes. In this article, three mechanisms for knowledge mobilization that have been suggested as important during the pandemic (urgency, engagement, technology) are reinterpreted from a critical communities of practice perspective. It is argued that learning driven by research communities in urgent contexts is moderated by institutional tensions, stakeholder power, and technostress.