If the story teased so far has a heavier emphasis on time and possibly space...

Some past collabs involve minor or small breaches in the dimensional wall. The raid could be caused by something similar on a much larger scale either through natural phenomenon or possibly a garlean lab royally screwing something up trying to recreate Allegan technology. In the end theres possibilities of a timewarp to the past or future, or it could be a separate dimension, a different shard world, or a complete alternate timeline caused by key events happening different in the past. (insert doc brown talking about how time splits at points due to different possible outcomes of events using a drawing on a chalkboard)