'Timmy Failure: Mistakes Were Made' is, simply put, not very good. The execution of the plot is underwhelming, while the ultra dry nature of the humour becomes tiresome quickly. I was giving it the benefit of the doubt for the most part, with the expectation of a decent pay off at the end... but that doesn't arrive.
Winslow Fegley (brother of Oakes Fegley from 'Pete's Dragon') is alright in the lead, but the only cast member I'll remember is Craig Robinson - I, truly, liked his character, Mr. Jenkins. Ophelia Lovibond and Wallace Shawn are OK, I guess. I don't really have anything against the cast, to be honest.
It's just everything else that gives this film a low rating from me. I will say I do like a few aspects. For example, there's a cool CGI polar bear from start-to-finish, but it literally never does anything of note. I also get the message they were aiming for, but they don't quite get there. I did find the dialogue good, in parts, though.
It's harmless and, evidently, some will find enjoyment in this. For me, it isn't anything worth noting in terms of Disney releases.