Thanks for passing by, and don't worry for the question. There is no dumb question (sometimes there are however dumb answers :D ).

If dark matter was being produced in the LHC, wouldn't it have affected the trajectories of charged particles differently? Or is that something already in the energy/momentum discrepancies you mentioned?

Being very weakly interacting, dark matter particles produced at the LHC leave the detector without interacting with anything. Nevertheless, the trajectories off all the other particles produced in the event are impacted as momentum is conserved. Therefore, there is an impact, that can be measured through energy-momentum conservation.

Does it clarify?

Cheers!