I really wish I hadn't set the dial to the Jurassic period. If only I had remembered that T-Rexes run faster than humans!

When we talk about regrets or things we want to change about the past, we use "wish" or "if only" followed by the past perfect tense (had + past participle).

Using the past simple (didn't set, remembered) would mean you are wishing for a change in the present, which doesn't help our running time traveler!