I came upon this (humorous) video where there are presented several incidents of the Swiss army accidentally marching into Liechtenstein due to bad map awareness and orientation. In the video they are called "accidental invasions". According to the video Switzerland even officially apologised for these incidents. In the comments there are even more anecdotes of the Swiss army accidentally ending up in other neighbouring countries like France and Italy. One comment goes as far as jokingly saying "So technically, Switzerland also accidentally invaded France with a one-man army" when a soldier going home fell asleep in a train and ended up in France.
These incidents happening during peace times between friendly countries with open borders between them, I found it off-putting at first to consider them invasions. But I guess this would have been a whole other story had other countries been involved.
Does this really count as an invasion? Or is it just a humorous device used in the video?