The circuit board that Willy attaches to the pool table for the guidance system has no component parts on it. Though every effort was made to try to hide the top side of the board, it can be seen briefly that it is blank and only has the circuit traces on the bottom.
Barney uses his pick to open the locked door to the pool hall. To pick such a lock, a torque lever is also needed. As he then enters, it clearly is shown there is no latch on the door frame.
At 20:00, the soundstage wall is clearly visible above the wall of Krebb's office.