Tim,
PMFJI. If you need to return the updated records, why don't you simply select them from inserted table? Something like this:

CREATE PROCEDURE dbo.GetSpotsByCompanyIDWithRange
(
	@CompanyID UniqueIdentifier,
	@StartRange DateTime,
	@EndRange DateTime,
	@Sentinel Bit,
	@SentinelMark VarChar
) 
AS
BEGIN
	SET NOCOUNT ON;
	-- Set the Sentinel Mark, Status, And Status Time
UPDATE TrackSpot
	SET SentinelMark = @SentinelMark,
		Record_Status_dt = @SetTime,
		Record_Status = "Sentinel Marked"
	WHERE s.CompanyID = @CompanyID
		AND Spot_Time >= @StartRange
		AND Spot_Time <= @EndRange
		AND Sentinel = @Sentinel

  
  SELECT * from inserted -- return the inserted rows
  -- I didn't list fields for simplicity
END

Cetin