Plot hole: It makes absolutely no sense that there would be over a dozen cops and soldiers in the lobby of the courthouse and leave only two cops to guard Lecter regardless that he was locked in the makeshift cell. Yes the plot needs a reason for him to easily escape but this still goes against every conceivable protocol for such a dangerous prisoner especially when there were dozens of armed personnel just in the scene alone when he was being transferred from the plane.
Plot hole: When Clarice visits Lecter in his new makeshift cell, she brings his drawings, which were left behind in Baltimore. She tells him how she saw the lambs being killed and heard them screaming, taking one lamb with her when she ran away. As the guards approached his cell after she leaves, the camera pans across the cell, taking in the drawings Clarice had brought, and the top one is a very detailed drawing of Clarice holding a spring lamb. She only told just told Lecter about the lamb, not enough time for him to have done that drawing.
Suggested correction: First; I do agree and support the mistake. But playing devil's advocate for a moment; she told him back in Baltimore about the ranch and how they had sheep and horses, so in theory he could have already started drawing back then and figure that a memory about the place was linked to those animals, adding the exact detail afterwards. Should also be noted that the guards approach the cell 'after she leaves', yes, but it's an 'after' that happens after she already flew back all the way from Memphis, so a few hours later.
Your last sentence corrects the mistake, the top drawing is new and wasn't brought by Clarice. You can see chalk on top of the drawing indicating he had just made it. Several hours passed between her delivering her story and him receiving his dinner.
