This paper focuses on the shifting terrain of mobile researchers beginning with an overview of research and research policy on "brain mobility", and then discussing what we call their optical illusions/delusions. Subsequently, our main purpose is to elaborate on a line of inquiry that offers richer notions of researcher mobility, connectivity and globalisation than those employed in current policies and their usual research base. Indeed we seek to conceptually enrich the field of research on "brain mobility" by bringing it into dialogue with anthropological discussions of cultural globalisation. We argue that global ethnography offers considerable potential as an alternative methodology particularly when accompanied by the notion of global assemblage. We unpack these concepts showing how we are deploying them in a current project of ours which is exploring the contemporary configurations of knowledge, culture and connection that come about through researchers movements, and which seeks to contribute to socio-cultural studies of contemporary knowledge flows and of global research governance.