Yes this is on backwards :p

SELECT * FROM gallery2 WHERE topic_id="1742341" UNION SELECT * FROM gallery2 WHERE topic_id="493796" UNION SELECT * FROM gallery2 WHERE topic_id="1499451" UNION SELECT * FROM gallery2 WHERE topic_id="798774" UNION SELECT * FROM gallery2 WHERE topic_id="838423" UNION SELECT * FROM gallery2 WHERE topic_id="1427757" UNION SELECT * FROM gallery2 WHERE topic_id="502570" UNION SELECT * FROM gallery2 WHERE topic_id="548468" UNION SELECT * FROM gallery2 WHERE topic_id="1501432" UNION SELECT * FROM gallery2 WHERE topic_id="1798042" UNION SELECT * FROM gallery2 WHERE topic_id="523472" UNION SELECT * FROM gallery2 WHERE topic_id="1583083" UNION SELECT * FROM gallery2 WHERE topic_id="1805146" UNION SELECT * FROM gallery2 WHERE topic_id="1665912" UNION SELECT * FROM gallery2 WHERE topic_id="1117791" UNION SELECT * FROM gallery2 WHERE topic_id="1146444"