Plot holes

Here is one of them. When Tim takes his sister to the past, she has all her memories from the future intact but when he decides to go back to the same future they have been in in the first place, she does seem to have no such memories, even though he does. Not clear if they decided together to go back to the original future, or he only left his sister in the past.

When Tim takes Kit Kat to the past, and back to the present again, she has new memories of being with Jay. But Tim doesn't have any new memories, of having and raising a different child.

- Tim and Mary do not age although years pass

- only male ones can time travel - greetings from the patriarchy. Are girs to0 stupid, or less worthy?
Ok this might not be a plothole as it is an "explained" rule in the film, but a clear plot hole is: Kitkat suddenly can time travel when holding her brothers hands in a dark closet, sure.

- the time travels lead to very linear changes (Tim changes an incident and not much else changes) BUT Tim's children are totally different when travelling before they were born?

- Tim's father explains: you cannot travel into the future. But they do not just travel into the past (and then relive it in a new way), they also travel 'back' from the past into an unknown future - maybe having other children (Tim), or boyfriends
(Kitkat). How can they return to the same closet/dark spot, when they might not even be in this location at that time in the new reality. Time travelling does not lead to Groundhog-day-lops, so does new-try-Tim just jump into closets for no reasons, so that his 'soul' or conscience can return from the past? How can they know more about their undone reality or feel more with the undone reality than with the new one, that now actually happend, while the first one never happened as it was undone? Tim's new child: total stranger, Tim's unborn child: 'his' child. It's not even understandible how they activate the return travel - it happens just like that? HIs father explains how to leave off to the past, and Tim just does it. He does not even ask: how to return. A movie does not need to explain everything, but: This returning to the future present remains a huge plot hole as it is a too important element not to be explained.