While Root and Shaw are having drinks, Shaw's glass is empty in the first shot but is completely filled in the next.
When Sen. Garrison meets with John Greer, they stand in front of a painting. The painting is "The Garden of Earthly Delights", by Hieronymus Bosch. While their meeting is set in a Washington, D.C. area museum, the actual painting by Bosch has been housed in the Museo del Prado in Madrid, Spain since 1939.