Though the Play based on JB Fletcher's book is stated several times to be opening on Broadway, outside the theatre after the starting credits, you can clearly see the stars on the Hollywood Walk of Fame. Also, the interior of the theatre matches no Broadway house of the period.
When Jessica says "oh no no, I still use my old bucket of bolts typewriter" a laugh is inserted into the middle of the sentence, to hide either a mistake or wrong word and it is very obvious. Angela Lansbury bobbles her line slightly when she says, "Oh, no, no. I still my use my good old bucket of bolts." It sounds as if "Jessica" chuckles at the joke she just made about her typewriter, or, less likely, that Angela chuckled about slightly flubbing her line.
Easterbrook (Dean Stockwell) refers to having been invited to "your little post-prandial party", when speaking about the premier after-party. "Post-prandial" means "after-meal". But Easterbrook is shown to be a pompous windbag, and simply not have known the proper meaning of what he said.
When Jessica quotes Moliere regarding "theatre being unpredictable", critic Elliot sarcastically says "Bravo, Mrs. Fletcher!". Surely he is educated and savvy enough to know the correct term would be "BRAVA".