What was the production code for "down to earth"?
CREATE TABLE "table1_20124413_3" (
  "num" text,
  "original_title" text,
  "directed_by" text,
  "written_by" text,
  "original_airdate" text,
  "production_code" text
);
SELECT "production_code" FROM "table1_20124413_3" WHERE "original_title"='\"Down to Earth\"';