The spell-check application of most word processing software programs would not catch a slip-up of these two words. Spell-check is looking for words that aren’t in its dictionary, and words that resemble words in its dictionary but are possibly spelled wrong. Spell-check isn’t perfect. It doesn’t know and can’t guess what word you wanted or what word you meant, it can only judge the words on the page. If you used words that are all spelled correctly, it gives you a pass anyway.
Autocorrect suggests words that start with the same letters. It suggests what word you may want to save time, but quite often, its suggestions couldn’t be more off base and produces humorous results.
Incontinent is an adjective. It describes a condition where a person or animal cannot control their bowel movements. Incontinence, the noun form, is the state of being incontinent.
Intercontinental is an adjective. It describes a thing or activity happening between two continents.
The following story uses both words correctly:
Irina, a secretary of state for Flanders, was under considerable stress in trying to negotiate a intercontinental trade deal with Cathay and Ceylon. Given her chronic acid reflux and colitis issues, she wasn’t sure if she’d make it through the weekend without incontinence and flare ups. This made her job extremely difficult.