cl_predictionlist

cl_predictionlist is a console variable available in all Source games. If cl_predictionlist is enabled, an overlay will be shown in the upper right-hand corner. This overlay shows all the entities that are currently using the Source prediction system (ie: running on both the client and server). The left-hand column shows the index of each entity, and the middle column shows the class names of the entities.

Once you know the index of the entity you need to debug, you can use cl_pdump.