You can do this in PPT 2002/2003

Click on the candy bar on the left. Go to Slide Show > Custom Animation. In
the animation task pane Select Add Effect < Motion Path > Right. Adjust the
distance the candy bar moves to the right by clicking on the motion path
indicator's right arrow and moving it to the left or right.

While keeping the candy bar on the left selected, go once again to the
animation task pane and choose Add Effect. This time select Exit > Zoom > In.
Adjust the settings for this second animation to Start With Previous. You'll
need to adjust timing for this second animation by selecting it in the Task
Pane, then selecting it's drop down menu and then selecting Show Advanced
Timeline. Adjust the timing by moving the orange bar so that it starts right
after the first animation.

Repeat this process for the candy bar on the right, reversing the paths as
needed.

Now insert your third candy bar in the middle of the other two. While it's
selected, go to Slide Show > Custom Animation. Select Add Effect > Entrance >
Fade.  Set it to start With Previous - it should start and end at the same
time as the explosion of the other two.