Is it necessary to insert a comma after 'movie'?

No, a comma is not necessary.

Also, fyi, I would change entitled to titled.

Why, Roberta?

I think the words are synonymous.

"Titled" is more exact in this instance. "Entitled" can mean "the name given to something" but it's primary meaning is "given a right or claim."

Brits might be more apt than Americans to use "entitled" in your sentence, however.

I use British English and that's why I used 'entitled'.

Yes Tang 'cause it affects meaning. Without the comma, you might have several favorites with the same title

Tut I disagree. Without the comma we might gather there are several movies with that title but that we want to describe our favorite

Without the comma, it would mean favorite among all the movies entitled "The Big Boss."

From now on, I ought to read all the replies first so I won't be redundant. On the other hand, it would balance the vote in favor of those who don't suffer from commaphobia.

I suffer from commaphilia, I swear. They tend to drip, you know.

We have a poster, thought by some to be a bot as it started out with wrecked language posts, but who/it now just repeats other's answers.

I'm glad to see you here, Sage, neat name.

We have another poster, unnamed, who sometimes begs to differ with Roberta, which is both annoying and sort of likeable and makes me giggle. Arguing with Roberta is dummass (how is that spelled?) but it is possible she may be wrong one or more times in some number of years, or using US usage instead of Brit usage. She's a long time major New York editor (etc.) and knows her beeswax. Also has some good threads of her own.

Welcome to a2k, enjoy.

In my opinion, the answer is YES.

I think that your sentence is just a shorter way to say "I want to tell you about my favorite movie, which is entitled 'The Big Boss.' "

As you can see, "which is entitled 'The Big Boss' " is a non-defining clause. That is, it is extra information but not essential to the meaning of your sentence.

The comma is not necessary, although writing this sentence with it won't be a mistake as well.