Debugging an application that uses a graphics API and faces a rendering error is a hard task even if we manage to record a trace of the API calls that lead to the error. Checking every call is not a feasible or scalable option, since there are potentially millions of calls in a recording. In this paper, we focus on the question of whether the number of API calls that need to be examined can be reduced by automatic techniques, and we describe how this can be achieved for the OpenGL API using the minimizing Delta Debugging algorithm. We present the results of an experiment on a real-life rendering issue, using a prototype implementation, showing a drastic reduction of the trace size (i.e., to less than 1‰ of the original number of calls) and positive impacts on the resource usage of the replay of the trace.