Around 42 minutes in, when Mark Greene, Craig, Jen and Rachel talk at the front of the house, there are a few bad edits where from one angle Jen is shown speaking, with no audio, lines she was previously already shown speaking.
After hitting his head on the table, when Mark swaps his blood soaked paper towel for a "clean" square of gauze you can clearly see it already has "blood" on it.
When the paramedics bring one of the patients (with the blue dress) into the trauma room, Carol looks directly at the camera for a second.
Dr. Ross states that he is going home to watch the Channel 11 Yule Log. Later, when he shows up at Nurse Hathaway's home, she says "I thought you were going to stay home and watch the Channel 9 Yule Log".