Game 5 in the best-of-seven series is on Wednesday at Toronto.
Miami's overtime effort was led by Justise Winslow's tip-in basket, Joe Johnson's two blocked shots, a layup by Goran Dragic and a steal and dunk by Wade.
In a low-scoring game, the offensive futility was symbolized by a Wade shot in overtime than got stuck on the rim, resulting in a jump ball.
The Raptors had a chance to win the game in regulation but Cory Joseph missed a 15-foot jumper at the buzzer. In the previous possession, Wade drove to the basket and tied the score with 12.6 seconds left.
Toronto got scoring from some unexpected sources -- 14 points each from DeMarre Carroll and Joseph.
In addition, emergency starter Bismack Biyombo, who replaced injured center Jonas Valanciunas, had a double-double with 13 points and 13 rebounds.
But Toronto's starting guards were largely ineffective.
Kyle Lowry had 10 points, and DeMar DeRozan, who was playing with a jammed right thumb, had nine points. Lowry fouled out with 1:58 left in the fourth quarter after he was called for an offensive infraction, hooking the defender with his off hand.
Miami got off to a hot start, shooting 55.6 percent and taking a 25-21 lead in the first quarter. Toronto shot just 36.8 percent.
The Heat extended their lead to 44-35 at halftime -- the first time in this series that Miami led at the break. Toronto shot just 22.7 percent in the second quarter.
Toronto, though, put together a 15-4 run to start the third quarter abd used that spurt to take a 62-60 lead after three quarters.
After shooting so poorly in the first half, Toronto made 64.7 percent in the third quarter. Carroll made 5-of-5 from the floor in the third as Toronto held Miami to 37.5 percent.
