It's elementary for Perl that @arrays and %hashes are flattened in list context, not only in the case of a foreach (LIST), but whenever the docs talk about "LIST" as parameter.

from perldata#List value constructors

LISTs do automatic interpolation of sublists. That is, when a LIST is evaluated, each element of the list is evaluated in list context, and the resulting list value is interpolated into LIST just as if each individual element were a member of LIST. Thus arrays and hashes lose their identity in a LIST--the list

(@foo,@bar,&SomeSub,%glarch)

contains all the elements of @foo followed by all the elements of @bar, followed by all the elements returned by the subroutine named SomeSub called in list context, followed by the key/value pairs of %glarch.

  DB<105> @a=1..3
 => (1, 2, 3)

  DB<106> @b=a..c
 => ("a", "b", "c")

  DB<107> @c=(@a,@b)
 => (1, 2, 3, "a", "b", "c")
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HTH! =)

It was not "trouble", and actually not a bad question, but learning to write small test programs to check your understanding is a very useful art. The same art applies when the question grows beyond anything one can answer for oneself, but then the art morphs into being able to create a small focused test script that others can use as a test bed for understanding your issue and providing a solution.