Before I get into this, I feel the need to explain what are time slips are, as it asked of me a number of times by those with a more conventional view of the world.
I will the do the best I can to define and explain what is either a paranormal concept or a scientific theory. The Time Slip Phenomenon, a person, or group of people, perceive that they have traveled across time, momentarily, displacing their ordinary timeline, permitting them experience and interact within what might be described as an alternate timeline or at least a past timeline.
That last part, the reports indicate the people physical interact with their environment, is what separates these reports from the psychic or clairvoyant phenomena. Often not realizing at first that are experiencing a phenomenon until after. While some people who have had these experiences, depict historical events, while others, more commonly, have seemingly random encounters with a nondescript timeline.
In the few case where physical evidence is offered, it is often of a photographic nature, or in one case the lack of, the images were missing from the roll of film. Of course this lack of evidence doesn’t sway me completely from believing that these people have had something happen to them. Today we could, under the right influence, be convinced, while using a fully immerse Virtual Reality device that we are personally experiencing a real event that is in fact a simulation. Why nobody has thought to bring back rock or other heirloom, I don’t know, but it would be helpful. The cynic in me suggests the reason for the lack of this physical evidence is because Big Foot is the Time Portly Gate keeper, and insures no goods are taken.
There are several other phenomenon that provide similar reports, most of which are of the UFO variety.
I offer to you a small handful of sites that discuss the matter and provide witness accounts.
From Mysterious Universe, Cases of Time Slips
From Report a UFO, Time Slips: A Strange Phenomenon
From Tech e Blog, 5 Bizarre Time Slip Cases Where People Might Have Actually Time Traveled
From the US National Library of Medicine National Institutes of Health, ‘Time slip’ phenomenon in adolescents and adults with autism spectrum disorders: case series
From USA Hitman, Time Slips / Time Travel