The website description for Detour, as well as the hard copy score, indicate that the required instrumentation includes a shared marimba. https://www.tapspace.com/percussion-ensemble/detour/
Both of these descriptions also clearly show two marimbas in the suggested setup. The written music requires two marimbas. For example, at Rehearsal A the two marimba parts are written to be played on the same pitches, meaning two players cannot play these parts while sharing an instrument.
There is also a stray treble clef sign in the Marimba 2 part in Measure 42 (likely a copy/paste holdover from Measure 20).
The shared marimba issue is the main one and is quite misleading and confusing. The score notes that marimba parts can be doubled if desired. With shared marimba parts, Detour can accommodate twice as many marimba players as there are instruments. Not so with non-shared parts.