Is this sentence.

Mr. and Mrs. Lopez's plane tickets, incidentally were found in the lobby.
Is this correct punctuation?

Remove the comma, and it'll be perfect.

Yes, the sentence "Mr. and Mrs. Lopez's plane tickets, incidentally were found in the lobby" is correct in terms of punctuation. However, there is a slight issue with the word order and clarity of the sentence.

To explain the punctuation, let's break it down:

- The sentence starts with a capital letter, which is the correct way to begin a sentence.
- The name "Mr. and Mrs. Lopez" is pluralized by adding an 's after the name, indicating possession. This is grammatically correct.
- The phrase "plane tickets" is followed by a comma. This comma is used to separate the phrase from the rest of the sentence.
- The word "incidentally" is introduced by a comma. This comma is used to set off the introductory word from the rest of the sentence.
- The sentence ends with a period, which is the correct way to end a statement.

However, it's worth noting that the word order in this sentence can be improved for clarity. A more clear and concise version could be: "Incidentally, Mr. and Mrs. Lopez's plane tickets were found in the lobby." This revised version places the introductory word at the beginning, making it easier to understand the intended meaning.