There's an ambiguity here between palindromic words and palindromic sentences (where punctuation and spacing are non-breaking):

"Go hang a salami, I'm a lasagna hog"

or

"A man, a plan, a canal, Panama"

though it seems that all of the answers (in the one tutorial and one round that I played) are single words, often slid in as character insertions. Just go light on the spacebar, apparently.

You wouldn't happen to be a fan of Jon Agee ?

It seems that every answer is a single word. I don't think it says that anywhere, but the few I've done seem to be that way.

There is no space bar on the on-screen keyboard on mobile, so it's not possible to type multiple words as well.

It wouldn't be accepted by a palindrome-detecting function but it would generally be accepted by puzzle-solving conventions (e.g. for crosswords), which normally ignore spaces.