There are several synonyms for the phrase "toppling over" that can be used to add variation and interest to your writing. One option is "tumbling," which has a sense of a sudden, uncontrolled fall. Another good choice is "pitching," which conveys a sense of something being thrown forward or tilting to one side. "Capsizing" is a particularly useful synonym for objects like boats or ships, suggesting a sudden loss of balance that sends them flipping over. "Falling over" is a more straightforward option, but it's still a good one to use if you need to convey a sense of something coming crashing down. Overall, there are many potential alternatives to "toppling over" that can help make your writing more engaging and dynamic.