以下の実行が通りません。
If init_id(i) = del_id(j) Then
の個所でインデックスの範囲外というエラーがでました。
配列に対して添字を()しているのが問題でしょうか？

Sub 次の問題()
Dim totalQuestions As Long, pastQuestions As Long, Nextnum As Long, n As Long
Dim init_id() As Variant, del_id() As Variant

totalQuestions = Worksheets("Play").Cells(Rows.Count, 1).End(xlUp).Row - 1
Randomize
Nextnum = Int(totalQuestions * Rnd + 1)
n = Worksheets("arrData").Cells(Rows.Count, "B").End(xlUp).Row + 1
Worksheets("arrData").Cells(n, "B") = Nextnum

init_id = Worksheets("Play").Range(Worksheets("Play").Cells(2, 1), Worksheets("Play").Cells(totalQuestions + 1, 1)).Value

pastQuestions = Worksheets("arrData").Cells(Rows.Count, 2).End(xlUp).Row - 1
del_id = Worksheets("arrData").Range(Worksheets("arrData").Cells(2, 2), Worksheets("arrData").Cells(pastQuestions + 1, 2)).Value

Dim i As Integer, j As Integer
For i = 1 To totalQuestions
For j = 1 To pastQuestions
If init_id(i) = del_id(j) Then
Debug.Print init_id(i).Value
End If
Next j
Next i

End Sub