When Sam - as Frank - tends to Mimi, he has the scissors in his right hand and the comb in the left. In the next shot when Mimi gets up, the comb is gone.
While Al and Sam are talking outside the salon, in a moment of frustration, Al taps Sam on the shoulder three times in succession. But of course, he wouldn't be able to do that if he were a hologram.
While explaining some history to Sam, Al refers to "Bensonhurst, New Jersey" which is actually a neighborhood in Brooklyn, NY - there is no such place in New Jersey.