When Victoria and Burke arrive and have just entered Burke holds his hand out to shake hands with Barnabas and Victoria's back is towards us. They go to a commercial and when they come back the sash has draped around her back has changed position (up slightly higher) although no time should have elapsed.
When Roger, Carolyn and Elizabeth start to go off to the party-- When Roger tells Elizabeth to come on-- you can see the shadow of the boom mic on the wall. When Elizabeth says her last word, the boom mic rises and moves off while they are walking out.